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Full vulnerability report · 2026
CVE-2026-109740High confidence

Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component

Mozilla · Firefox

9.6CriticalCVSS 3.1
Recommended action
Within 7 days

Critical technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:Critical, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 0.35% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Mozilla Firefox and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Distribution package intelligence

Release-specific package status

Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

11 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcefirefox-esrNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 4 Nov 2026
Debian trixietrixie · sourcethunderbirdNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 4 Nov 2026
Debian bookwormbookworm · sourcefirefox-esrNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 4 Nov 2026
Debian bookwormbookworm · sourcethunderbirdNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 4 Nov 2026
Debian forkyforky · sourcefirefox-esrNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 4 Nov 2026
Debian forkyforky · sourcethunderbirdNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 4 Nov 2026
Debian sidsid · sourcefirefoxNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 4 Nov 2026
Debian sidsid · sourcefirefox-esrNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 4 Nov 2026
Debian sidsid · sourcethunderbirdNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 4 Nov 2026
Ubuntu 24.04 LTSnoble · standard archivemozjs102Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 4 Nov 2026
Ubuntu 24.04 LTSnoble · standard archivemozjs115Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical Ubuntu Security ↗Source updated 4 Nov 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

2 current
CVE-2026-109740 · CSAF 2.0 · revision 8 · interimSUSE Product Security TeamCVE-2026-109740
165 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • MozillaFirefox as component of SUSE Linux Enterprise Desktop 15 SP7
  • MozillaFirefox-devel as component of SUSE Linux Enterprise Desktop 15 SP7
  • MozillaFirefox-translations-common as component of SUSE Linux Enterprise Desktop 15 SP7
  • MozillaFirefox-translations-other as component of SUSE Linux Enterprise Desktop 15 SP7
  • MozillaThunderbird as component of SUSE Linux Enterprise Desktop 15 SP7
  • MozillaThunderbird-translations-common as component of SUSE Linux Enterprise Desktop 15 SP7
  • MozillaThunderbird-translations-other as component of SUSE Linux Enterprise Desktop 15 SP7
  • MozillaFirefox as component of SUSE Linux Enterprise High Performance Computing 12 SP5
  • MozillaFirefox-devel as component of SUSE Linux Enterprise High Performance Computing 12 SP5
  • MozillaFirefox-translations-common as component of SUSE Linux Enterprise High Performance Computing 12 SP5
  • MozillaFirefox as component of SUSE Linux Enterprise High Performance Computing 15 SP1
  • MozillaFirefox-devel as component of SUSE Linux Enterprise High Performance Computing 15 SP1
Summary
Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.
Remediation
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
CVE-2026-109740 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityfirefox: firefox: Sandbox escape via incorrect boundary conditions in Win32 widget
14 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • rhel10/firefox-flatpak as a component of Red Hat Enterprise Linux 10
  • rhel10/thunderbird-flatpak as a component of Red Hat Enterprise Linux 10
  • thunderbird as a component of Red Hat Enterprise Linux 10
  • thunderbird.src as a component of Red Hat Enterprise Linux 10
  • firefox as a component of Red Hat Enterprise Linux 6
  • firefox.src as a component of Red Hat Enterprise Linux 6
  • thunderbird as a component of Red Hat Enterprise Linux 6
  • thunderbird.src as a component of Red Hat Enterprise Linux 6
  • firefox as a component of Red Hat Enterprise Linux 7
  • firefox.src as a component of Red Hat Enterprise Linux 7
  • thunderbird as a component of Red Hat Enterprise Linux 7
  • thunderbird.src as a component of Red Hat Enterprise Linux 7
Summary
A flaw was found in Firefox. Incorrect boundary condition handling in the Win32 widget component allows an attacker to escape the browser's restricted sandbox environment. An attacker who has compromised a sandboxed content process could exploit this vulnerability to achieve privilege escalation and execute arbitrary code on the underlying operating system.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-98502

No EUVD known-exploited evidence

Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
0.0
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

Critical technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

What

Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

Why

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

Why

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Improper Restriction of Operations within the Bounds of a Memory Buffer → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
Required interaction required
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Changed: exploitation can affect a different security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-119 ↗

CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer. The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SChangedScope: The attack can affect a component governed by a different security authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-119
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-98502Official EUVD mapping

Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

Official EUVD record ↗
BSI · German · WID-SEC-2026-3942Mozilla Firefox und Thunderbrid: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Mozilla Firefox und Mozilla Thunderbrid ausnutzen, um seine Privilegien zu erhöhen, Sicherheitsmaßnahmen zu umgehen, Spoofing-Angriffe durchzuführen, Daten offenzulegen oder zu manipulieren, Denial-of-Service-Zustände zu verursachen oder andere, nicht näher spezifizierte Angriffe durchzuführen.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1305Avis du CERT-FR

731 Référence CVE CVE-2026-109732 https://www.cve.org/CVERecord?id=CVE-2026-109732 Référence CVE CVE-2026-109733 https://www.cve.org/CVERecord?id=CVE-2026-109733 Référence CVE CVE-2026-109734 https://www.cve.org/CVERecord?id=CVE-2026-109734 Référence CVE CVE-2026-109735 https://www.cve.org/CVERecord?id=CVE-2026-109735 Référence CVE CVE-2026-109736 https://www.cve.org/CVERecord?id=CVE-2026-109736 Référence CVE CVE-2026-109737 https://www.cve.org/CVERecord?id=CVE-2026-109737 Référence CVE CVE-2026-109738 https://www.cve.org/CVERecord?id=CVE-2026-109738 Référence CVE CVE-2026-109739 https://www.cve.org/CVERecord?id=CVE-2026-109739 Référence CVE CVE-2026-109740 https://www.cve.org/CVERecord?id=CVE-2026-109740 Référence CVE CVE-2026-109741 https://www.cve.org/CVERecord?id=CVE-2026-109741 Référence CVE CVE-2026-109742 https://www.cve.org/CVERecord?id=CVE-2026-109742 Référence CVE CVE-2026-109743 https://www.cve.org/CVERecord?id=CVE-2026-109743 Référence CVE CVE-2026-109744 https://www.cve.org/CVERecord?id=CVE-2026-109744 Référence CVE CVE-2026-109745 https://www.cve.org/CVERecord?id=CVE-2026-109745 Référence CVE CVE-2026-109746 https://www.cve.org/CVERecord?id=CVE-2026-109746 Référence CVE CVE-2026-109747 https://www.cve.org/CVERecord?id=CVE-2026-109747 Référence CVE CVE-2026-109748 https://www.cve.o

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
Fixed
Action
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
Official vendor articles4 stored documents

Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.

  • Security Vulnerabilities fixed in Firefox 158 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 29 Oct 2026Security Vulnerabilities fixed in Firefox 158 Announced October 13, 2026 Impact high Products Firefox Fixed in Firefox 158 Note : We have changed how we publish advisories. We no longer roll all internally identified memory safety vulnerabilities into a single CVE and are now issuing an advisory for every indivi
  • Security Vulnerabilities fixed in Firefox ESR 153.5 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 29 Oct 2026Security Vulnerabilities fixed in Firefox ESR 153.5 Announced October 13, 2026 Impact high Products Firefox ESR Fixed in Firefox ESR 153.5 Note : We have changed how we publish advisories. We no longer roll all internally identified memory safety vulnerabilities into a single CVE and are now issuing an advisory
  • Security Vulnerabilities fixed in Thunderbird 158 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 29 Oct 2026Security Vulnerabilities fixed in Thunderbird 158 Announced October 13, 2026 Impact high Products Thunderbird Fixed in Thunderbird 158 Many of these flaws cannot be exploited through email in the Thunderbird product because scripting is disabled when reading mail, however they may pose risks in browser or browse
  • Security Vulnerabilities fixed in Thunderbird 153.5 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 29 Oct 2026Security Vulnerabilities fixed in Thunderbird 153.5 Announced October 13, 2026 Impact high Products Thunderbird Fixed in Thunderbird 153.5 Many of these flaws cannot be exploited through email in the Thunderbird product because scripting is disabled when reading mail, however they may pose risks in browser or br
04

Evidence and provenance

Published 13 Oct 2026 · Last source change 19 Oct 2026, 11:52 UTC · CWE-119 · Improper Restriction of Operations within the Bounds of a Memory Buffer

CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-10-14
European sourceENISA EUVD · EUVD-2026-98502
Product sourceVendor CSAF · SUSE Product Security Team
Remediation sourceVendor CSAF · SUSE Product Security Team
CWE sourceCISA ADP
NVD statusNVD not scheduled

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    rhel10/firefox-flatpak as a component of Red Hat Enterprise Linux 10; rhel10/thunderbird-flatpak as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 10; thunderbird.src as a component of Red Hat Enterprise Linux 10; firefox as a component of Red Hat Enterprise Linux 6; firefox.src as a component of Red Hat Enterprise Linux 6; thunderbird as a component of Red Hat Enterprise Linux 6; thunderbird.src as a component of Red Hat Enterprise Linux 6; firefox as a component of Red Hat Enterprise Linux 7; firefox.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 7; thunderbird.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 8; thunderbird.src as a component of Red Hat Enterprise Linux 8; thunderbird as a component of Red Hat Enterprise Linux 9; thunderbird.src as a component of Red Hat Enterprise Linux 9 · Fixed: firefox-0:153.5.0-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el10_2.src as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debuginfo-0:153.5.0-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debuginfo-0:153.5.0-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debuginfo-0:153.5.0-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debuginfo-0:153.5.0-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debugsource-0:153.5.0-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debugsource-0:153.5.0-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debugsource-0:153.5.0-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debugsource-0:153.5.0-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el8_10.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el8_10.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el8_10.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el8_10.src as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el8_10.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debuginfo-0:153.5.0-1.el8_10.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debuginfo-0:153.5.0-1.el8_10.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debuginfo-0:153.5.0-1.el8_10.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debuginfo-0:153.5.0-1.el8_10.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debugsource-0:153.5.0-1.el8_10.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debugsource-0:153.5.0-1.el8_10.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debugsource-0:153.5.0-1.el8_10.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debugsource-0:153.5.0-1.el8_10.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el9_8.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 9); firefox-0:153.5.0-1.el9_8.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 9); firefox-0:153.5.0-1.el9_8.s390x as a component of Red Hat Enterprise Linux AppStream (v. 9); firefox-0:153.5.0-1.el9_8.src as a component of Red Hat Enterprise Linux AppStream (v. 9); and 13 more
    After
    rhel10/firefox-flatpak as a component of Red Hat Enterprise Linux 10; rhel10/thunderbird-flatpak as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 10; thunderbird.src as a component of Red Hat Enterprise Linux 10; firefox as a component of Red Hat Enterprise Linux 6; firefox.src as a component of Red Hat Enterprise Linux 6; thunderbird as a component of Red Hat Enterprise Linux 6; thunderbird.src as a component of Red Hat Enterprise Linux 6; firefox as a component of Red Hat Enterprise Linux 7; firefox.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 7; thunderbird.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 8; thunderbird.src as a component of Red Hat Enterprise Linux 8 · Fixed: firefox-0:153.5.0-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el10_2.src as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debuginfo-0:153.5.0-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debuginfo-0:153.5.0-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debuginfo-0:153.5.0-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debuginfo-0:153.5.0-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debugsource-0:153.5.0-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debugsource-0:153.5.0-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debugsource-0:153.5.0-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debugsource-0:153.5.0-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el8_10.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el8_10.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el8_10.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el8_10.src as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el8_10.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debuginfo-0:153.5.0-1.el8_10.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debuginfo-0:153.5.0-1.el8_10.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debuginfo-0:153.5.0-1.el8_10.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debuginfo-0:153.5.0-1.el8_10.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debugsource-0:153.5.0-1.el8_10.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debugsource-0:153.5.0-1.el8_10.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debugsource-0:153.5.0-1.el8_10.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debugsource-0:153.5.0-1.el8_10.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el9_8.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 9); firefox-0:153.5.0-1.el9_8.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 9); firefox-0:153.5.0-1.el9_8.s390x as a component of Red Hat Enterprise Linux AppStream (v. 9); firefox-0:153.5.0-1.el9_8.src as a component of Red Hat Enterprise Linux AppStream (v. 9); and 26 more
    Red Hat Product Security ↗
  2. Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-109740 to remediation: access.redhat.com/CVE-2026-109740.
    Before
    remediation: access.redhat.com/CVE-2026-109740
    After
    remediation: access.redhat.com/CVE-2026-109740
    Red Hat Product Security ↗
  3. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    Red Hat Product Security ↗
  4. Affected versionsThe structured affected or fixed version information changed.
    Before
    firefox as a component of Red Hat Enterprise Linux 10; firefox.src as a component of Red Hat Enterprise Linux 10; rhel10/firefox-flatpak as a component of Red Hat Enterprise Linux 10; rhel10/thunderbird-flatpak as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 10; thunderbird.src as a component of Red Hat Enterprise Linux 10; firefox as a component of Red Hat Enterprise Linux 6; firefox.src as a component of Red Hat Enterprise Linux 6; thunderbird as a component of Red Hat Enterprise Linux 6; thunderbird.src as a component of Red Hat Enterprise Linux 6; firefox as a component of Red Hat Enterprise Linux 7; firefox.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 7; thunderbird.src as a component of Red Hat Enterprise Linux 7; firefox as a component of Red Hat Enterprise Linux 8; firefox.src as a component of Red Hat Enterprise Linux 8; thunderbird as a component of Red Hat Enterprise Linux 8; thunderbird.src as a component of Red Hat Enterprise Linux 8; firefox as a component of Red Hat Enterprise Linux 9; firefox-x11 as a component of Red Hat Enterprise Linux 9; firefox.src as a component of Red Hat Enterprise Linux 9; thunderbird as a component of Red Hat Enterprise Linux 9; thunderbird.src as a component of Red Hat Enterprise Linux 9
    After
    rhel10/firefox-flatpak as a component of Red Hat Enterprise Linux 10; rhel10/thunderbird-flatpak as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 10; thunderbird.src as a component of Red Hat Enterprise Linux 10; firefox as a component of Red Hat Enterprise Linux 6; firefox.src as a component of Red Hat Enterprise Linux 6; thunderbird as a component of Red Hat Enterprise Linux 6; thunderbird.src as a component of Red Hat Enterprise Linux 6; firefox as a component of Red Hat Enterprise Linux 7; firefox.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 7; thunderbird.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 8; thunderbird.src as a component of Red Hat Enterprise Linux 8; thunderbird as a component of Red Hat Enterprise Linux 9; thunderbird.src as a component of Red Hat Enterprise Linux 9 · Fixed: firefox-0:153.5.0-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el10_2.src as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debuginfo-0:153.5.0-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debuginfo-0:153.5.0-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debuginfo-0:153.5.0-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debuginfo-0:153.5.0-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debugsource-0:153.5.0-1.el10_2.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debugsource-0:153.5.0-1.el10_2.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debugsource-0:153.5.0-1.el10_2.s390x as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-debugsource-0:153.5.0-1.el10_2.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 10); firefox-0:153.5.0-1.el8_10.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el8_10.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el8_10.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el8_10.src as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el8_10.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debuginfo-0:153.5.0-1.el8_10.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debuginfo-0:153.5.0-1.el8_10.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debuginfo-0:153.5.0-1.el8_10.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debuginfo-0:153.5.0-1.el8_10.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debugsource-0:153.5.0-1.el8_10.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debugsource-0:153.5.0-1.el8_10.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debugsource-0:153.5.0-1.el8_10.s390x as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-debugsource-0:153.5.0-1.el8_10.x86_64 as a component of Red Hat Enterprise Linux AppStream (v. 8); firefox-0:153.5.0-1.el9_8.aarch64 as a component of Red Hat Enterprise Linux AppStream (v. 9); firefox-0:153.5.0-1.el9_8.ppc64le as a component of Red Hat Enterprise Linux AppStream (v. 9); firefox-0:153.5.0-1.el9_8.s390x as a component of Red Hat Enterprise Linux AppStream (v. 9); firefox-0:153.5.0-1.el9_8.src as a component of Red Hat Enterprise Linux AppStream (v. 9); and 13 more
    Red Hat Product Security ↗
  5. Affected versionsThe structured affected or fixed version information changed.
    Before
    firefox as a component of Red Hat Enterprise Linux 10; firefox.src as a component of Red Hat Enterprise Linux 10; rhel10/thunderbird-flatpak as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 10; thunderbird.src as a component of Red Hat Enterprise Linux 10; firefox as a component of Red Hat Enterprise Linux 6; firefox.src as a component of Red Hat Enterprise Linux 6; thunderbird as a component of Red Hat Enterprise Linux 6; thunderbird.src as a component of Red Hat Enterprise Linux 6; firefox as a component of Red Hat Enterprise Linux 7; firefox.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 7; thunderbird.src as a component of Red Hat Enterprise Linux 7; firefox as a component of Red Hat Enterprise Linux 8; firefox.src as a component of Red Hat Enterprise Linux 8; thunderbird as a component of Red Hat Enterprise Linux 8; thunderbird.src as a component of Red Hat Enterprise Linux 8; firefox as a component of Red Hat Enterprise Linux 9; firefox-x11 as a component of Red Hat Enterprise Linux 9; firefox.src as a component of Red Hat Enterprise Linux 9; thunderbird as a component of Red Hat Enterprise Linux 9; thunderbird.src as a component of Red Hat Enterprise Linux 9
    After
    firefox as a component of Red Hat Enterprise Linux 10; firefox.src as a component of Red Hat Enterprise Linux 10; rhel10/firefox-flatpak as a component of Red Hat Enterprise Linux 10; rhel10/thunderbird-flatpak as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 10; thunderbird.src as a component of Red Hat Enterprise Linux 10; firefox as a component of Red Hat Enterprise Linux 6; firefox.src as a component of Red Hat Enterprise Linux 6; thunderbird as a component of Red Hat Enterprise Linux 6; thunderbird.src as a component of Red Hat Enterprise Linux 6; firefox as a component of Red Hat Enterprise Linux 7; firefox.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 7; thunderbird.src as a component of Red Hat Enterprise Linux 7; firefox as a component of Red Hat Enterprise Linux 8; firefox.src as a component of Red Hat Enterprise Linux 8; thunderbird as a component of Red Hat Enterprise Linux 8; thunderbird.src as a component of Red Hat Enterprise Linux 8; firefox as a component of Red Hat Enterprise Linux 9; firefox-x11 as a component of Red Hat Enterprise Linux 9; firefox.src as a component of Red Hat Enterprise Linux 9; thunderbird as a component of Red Hat Enterprise Linux 9; thunderbird.src as a component of Red Hat Enterprise Linux 9
    Red Hat Product Security ↗
  6. Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-109740 to remediation: access.redhat.com/CVE-2026-109740.
    Before
    remediation: access.redhat.com/CVE-2026-109740
    After
    remediation: access.redhat.com/CVE-2026-109740
    Red Hat Product Security ↗
  7. Affected versionsThe structured affected or fixed version information changed.
    Before
    firefox as a component of Red Hat Enterprise Linux 10; firefox.src as a component of Red Hat Enterprise Linux 10; firefox as a component of Red Hat Enterprise Linux 7; firefox.src as a component of Red Hat Enterprise Linux 7; firefox as a component of Red Hat Enterprise Linux 8; firefox.src as a component of Red Hat Enterprise Linux 8; firefox as a component of Red Hat Enterprise Linux 9; firefox-x11 as a component of Red Hat Enterprise Linux 9; firefox.src as a component of Red Hat Enterprise Linux 9
    After
    firefox as a component of Red Hat Enterprise Linux 10; firefox.src as a component of Red Hat Enterprise Linux 10; rhel10/thunderbird-flatpak as a component of Red Hat Enterprise Linux 10; thunderbird as a component of Red Hat Enterprise Linux 10; thunderbird.src as a component of Red Hat Enterprise Linux 10; firefox as a component of Red Hat Enterprise Linux 6; firefox.src as a component of Red Hat Enterprise Linux 6; thunderbird as a component of Red Hat Enterprise Linux 6; thunderbird.src as a component of Red Hat Enterprise Linux 6; firefox as a component of Red Hat Enterprise Linux 7; firefox.src as a component of Red Hat Enterprise Linux 7; thunderbird as a component of Red Hat Enterprise Linux 7; thunderbird.src as a component of Red Hat Enterprise Linux 7; firefox as a component of Red Hat Enterprise Linux 8; firefox.src as a component of Red Hat Enterprise Linux 8; thunderbird as a component of Red Hat Enterprise Linux 8; thunderbird.src as a component of Red Hat Enterprise Linux 8; firefox as a component of Red Hat Enterprise Linux 9; firefox-x11 as a component of Red Hat Enterprise Linux 9; firefox.src as a component of Red Hat Enterprise Linux 9; thunderbird as a component of Red Hat Enterprise Linux 9; thunderbird.src as a component of Red Hat Enterprise Linux 9
    Red Hat Product Security ↗
  8. SeveritySeverity changed from Unknown to Critical.
    Before
    Unknown
    After
    Critical
    CISA ADP ↗
  9. CVSS scoreCVSS score changed from not recorded to 9.6 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H).
    Before
    not recorded
    After
    9.6 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H)
    CISA ADP ↗
  10. ENISA EUVD mappingEUVD-2026-98502 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-98502"}
    ENISA EUVD ↗
  11. Vendor guidanceAuthoritative vendor guidance changed: added remediation: bugzilla.mozilla.org/show_bug.cgi?id=2057113; removed remediation: mozilla.org/mfsa2026-109.
    Before
    remediation: mozilla.org/mfsa2026-109
    After
    remediation: bugzilla.mozilla.org/show_bug.cgi?id=2057113
    CNA ↗
  12. Vendor guidanceAuthoritative vendor guidance changed: added remediation: mozilla.org/mfsa2026-109; removed remediation: bugzilla.mozilla.org/show_bug.cgi?id=2057113.
    Before
    remediation: bugzilla.mozilla.org/show_bug.cgi?id=2057113
    After
    remediation: mozilla.org/mfsa2026-109
    CNA ↗
  13. Affected versionsThe structured affected or fixed version information changed.
    Before
    See the vendor and CVE records for the affected range. · Fixed: Firefox: 153.5 ≤ 153.*, 158 ≤ *
    After
    See the vendor and CVE records for the affected range. · Fixed: Firefox: 153.5 ≤ 153.*, 158 ≤ *; Thunderbird: 153.5 ≤ 153.*, 158 ≤ *
    CNA ↗
  14. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-98502↗Vendor CSAF · SUSE Product Security Team↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-109740 · cve.blacktree.nl