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Full vulnerability report · 2026
CVE-2026-92052High confidence

Privilege escalation due to uninitialized memory in the Graphics: CanvasWebGL component

Mozilla · Firefox

8.8HighCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 0.26% 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 30 daysRemediation target: Within 180 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.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

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.

7 package states
Package result overrides the generic status

BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 1 affected package state shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.

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 · sourcethunderbirdNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 29 Sep 2026
Debian bookwormbookworm · sourcethunderbirdNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 29 Sep 2026
Debian forkyforky · sourcethunderbirdAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 29 Sep 2026
Debian sidsid · sourcefirefoxVendor fix publishedDebian records a fixed source-package version for this release.156.0-1Debian Security Tracker ↗Source updated 29 Sep 2026
Debian sidsid · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:153.3.0esr-1Debian Security Tracker ↗Source updated 29 Sep 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 29 Sep 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 29 Sep 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-2026-92052 · CSAF 2.0 · revision 7 · interimSUSE Product Security TeamCVE-2026-92052
80 known affected

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

  • 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 15 SP1
  • MozillaFirefox-devel as component of SUSE Linux Enterprise High Performance Computing 15 SP1
  • MozillaFirefox-translations-common as component of SUSE Linux Enterprise High Performance Computing 15 SP1
  • MozillaFirefox-translations-other as component of SUSE Linux Enterprise High Performance Computing 15 SP1
  • MozillaFirefox as component of SUSE Linux Enterprise High Performance Computing 15 SP2
  • MozillaFirefox-devel as component of SUSE Linux Enterprise High Performance Computing 15 SP2
  • MozillaFirefox-translations-common as component of SUSE Linux Enterprise High Performance Computing 15 SP2
  • MozillaFirefox-translations-other as component of SUSE Linux Enterprise High Performance Computing 15 SP2
  • MozillaFirefox as component of SUSE Linux Enterprise High Performance Computing 15 SP3
Summary
Privilege escalation due to uninitialized memory in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.
Remediation
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
CVE-2026-92052 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityfirefox: thunderbird: Privilege escalation due to uninitialized memory in the Graphics: CanvasWebGL component
23 known not affected

The vendor explicitly states that these products are not affected by this CVE.

  • 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
Summary
A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue: Privilege escalation due to uninitialized memory in the Graphics: CanvasWebGL component
Remediation
No remediation text is recorded.
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-2026-78515

No EUVD known-exploited evidence

Privilege escalation due to uninitialized memory in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.

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
8.8 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

Privilege escalation due to uninitialized memory in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.

What

Privilege escalation due to uninitialized memory in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.

Why

The code uses a variable that has not been initialized, leading to unpredictable or unintended results.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may gain additional privileges.

What

Privilege escalation due to uninitialized memory in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.

Why

The code uses a variable that has not been initialized, leading to unpredictable or unintended results.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may gain additional privileges.

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 → Use of Uninitialized Variable → gain additional privileges
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
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-457 ↗

CWE-457: Use of Uninitialized Variable. The code uses a variable that has not been initialized, leading to unpredictable or unintended results.

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:U/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.SUnchangedScope: The security impact remains within the vulnerable component's 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.
NetworkUnauthenticatedPrivilege escalationCWE-457
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-78515Official EUVD mapping

Privilege escalation due to uninitialized memory in the Graphics: CanvasWebGL component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.

Official EUVD record ↗
BSI · German · WID-SEC-2026-3375Mozilla Firefox und Thunderbird: Mehrere Schwachstellen

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

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1183Multiples vulnérabilités dans les produits Mozilla

d?id=CVE-2026-92043 Référence CVE CVE-2026-92044 https://www.cve.org/CVERecord?id=CVE-2026-92044 Référence CVE CVE-2026-92045 https://www.cve.org/CVERecord?id=CVE-2026-92045 Référence CVE CVE-2026-92046 https://www.cve.org/CVERecord?id=CVE-2026-92046 Référence CVE CVE-2026-92047 https://www.cve.org/CVERecord?id=CVE-2026-92047 Référence CVE CVE-2026-92048 https://www.cve.org/CVERecord?id=CVE-2026-92048 Référence CVE CVE-2026-92049 https://www.cve.org/CVERecord?id=CVE-2026-92049 Référence CVE CVE-2026-92050 https://www.cve.org/CVERecord?id=CVE-2026-92050 Référence CVE CVE-2026-92051 https://www.cve.org/CVERecord?id=CVE-2026-92051 Référence CVE CVE-2026-92052 https://www.cve.org/CVERecord?id=CVE-2026-92052 Référence CVE CVE-2026-92053 https://www.cve.org/CVERecord?id=CVE-2026-92053 Référence CVE CVE-2026-92054 https://www.cve.org/CVERecord?id=CVE-2026-92054 Référence CVE CVE-2026-92055 https://www.cve.org/CVERecord?id=CVE-2026-92055 Référence CVE CVE-2026-92056 https://www.cve.org/CVERecord?id=CVE-2026-92056 Référence CVE CVE-2026-92057 https://www.cve.org/CVERecord?id=CVE-2026-92057 Référence CVE CVE-2026-92058 https://www.cve.org/CVERecord?id=CVE-2026-92058 Référence CVE CVE-2026-92059 https://www.cve.org/CVERecord?id=CVE-2026-92059 Référence CVE CVE-2026-92060 https://www.cve.org/CVERecord?id=

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.
Fix availability varies by product
Affected
Fixed
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
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 156 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 26 Sep 2026Security Vulnerabilities fixed in Firefox 156 Announced September 15, 2026 Impact high Products Firefox Fixed in Firefox 156 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 indi
  • Security Vulnerabilities fixed in Firefox ESR 153.3 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 26 Sep 2026Security Vulnerabilities fixed in Firefox ESR 153.3 Announced September 15, 2026 Impact high Products Firefox ESR Fixed in Firefox ESR 153.3 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 advisor
  • Security Vulnerabilities fixed in Thunderbird 156 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 26 Sep 2026Security Vulnerabilities fixed in Thunderbird 156 Announced September 15, 2026 Impact high Products Thunderbird Fixed in Thunderbird 156 In general, these flaws cannot be exploited through email in the Thunderbird product because scripting is disabled when reading mail, but are potentially risks in browser or br
  • Security Vulnerabilities fixed in Thunderbird 153.3 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 26 Sep 2026Security Vulnerabilities fixed in Thunderbird 153.3 Announced September 16, 2026 Impact high Products Thunderbird Fixed in Thunderbird 153.3 In general, these flaws cannot be exploited through email in the Thunderbird product because scripting is disabled when reading mail, but are potentially risks in browser o
04

Evidence and provenance

Published 15 Sept 2026 · Last source change 16 Sept 2026, 14:24 UTC · CWE-457 · Use of Uninitialized Variable

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 2026-09-16
European sourceENISA EUVD · EUVD-2026-78515
Product sourceVendor CSAF · SUSE Product Security Team
Remediation sourceVendor CSAF · SUSE Product Security Team
CWE sourceCISA ADP
NVD statusNVD awaiting enrichment

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

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: added remediation: bugzilla.mozilla.org/show_bug.cgi?id=2061499; removed remediation: mozilla.org/mfsa2026-96.
    Before
    remediation: mozilla.org/mfsa2026-96
    After
    remediation: bugzilla.mozilla.org/show_bug.cgi?id=2061499
    CNA ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added remediation: mozilla.org/mfsa2026-96; removed remediation: bugzilla.mozilla.org/show_bug.cgi?id=2061499.
    Before
    remediation: bugzilla.mozilla.org/show_bug.cgi?id=2061499
    After
    remediation: mozilla.org/mfsa2026-96
    CNA ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    See the vendor and CVE records for the affected range. · Fixed: Firefox: 153.3 ≤ 153.*, 156 ≤ *; Thunderbird: 156 ≤ *
    After
    See the vendor and CVE records for the affected range. · Fixed: Firefox: 153.3 ≤ 153.*, 156 ≤ *; Thunderbird: 153.3 ≤ 153.*, 156 ≤ *
    CNA ↗
  4. ENISA EUVD mappingEUVD-2026-78515 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-78515"}
    ENISA EUVD ↗
  5. Affected versionsThe structured affected or fixed version information changed.
    Before
    See the vendor and CVE records for the affected range. · Fixed: Firefox: 153.3 ≤ 153.*, 156 ≤ *
    After
    See the vendor and CVE records for the affected range. · Fixed: Firefox: 153.3 ≤ 153.*, 156 ≤ *; Thunderbird: 156 ≤ *
    CNA ↗
  6. SeveritySeverity changed from Unknown to High.
    Before
    Unknown
    After
    High
    CISA ADP ↗
  7. CVSS scoreCVSS score changed from not recorded to 8.8 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).
    Before
    not recorded
    After
    8.8 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)
    CISA ADP ↗
  8. 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-2026-78515↗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-2026-92052 · cve.blacktree.nl