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Full vulnerability report · 2026
CVE-2026-100823High confidence

Spoofing issue in the Downloads component in Firefox for Android

Mozilla · Firefox

5.4MediumCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 164 structured product or package states 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 severityMediumOperational priority:High, raised one band.upgradedsince 1 Oct 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • EPSS is 0.16% 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.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

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 164 structured product or package states 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.

3 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 sidsid · sourcefirefoxNot affectedDebian marks this release not affected (fixed-version marker 0).Not published in this feedDebian Security Tracker ↗Source updated 5 Oct 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 Oct 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 Oct 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.

1 current
CVE-2026-100823 · CSAF 2.0 · revision 3 · interimSUSE Product Security TeamCVE-2026-100823
164 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
Spoofing issue in the Downloads component in Firefox for Android. This vulnerability was fixed in Firefox 157.
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-2026-88802

No EUVD known-exploited evidence

Spoofing issue in the Downloads component in Firefox for Android. This vulnerability was fixed in Firefox 157.

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

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 164 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

Spoofing issue in the Downloads component in Firefox for Android. This vulnerability was fixed in Firefox 157.

What

Spoofing issue in the Downloads component in Firefox for Android. This vulnerability was fixed in Firefox 157.

Why

The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.

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

Spoofing issue in the Downloads component in Firefox for Android. This vulnerability was fixed in Firefox 157.

Why

The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.

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.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → User Interface (UI) Misrepresentation of Critical Information → 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
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-451 ↗

CWE-451: User Interface (UI) Misrepresentation of Critical Information. The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.

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:L/I:N/A:L

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.CLowConfidentiality impact: A successful attack can cause a limited loss.INoneIntegrity impact: No direct loss is represented by this metric.ALowAvailability impact: A successful attack can cause a limited 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-451Public exploit reference
A

Official authority intelligence

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

ENISA EUVD · EUVD-2026-88802Official EUVD mapping

Spoofing issue in the Downloads component in Firefox for Android. This vulnerability was fixed in Firefox 157.

Official EUVD record ↗
BSI · German · WID-SEC-2026-3654Mozilla Firefox, Firefox ESR und Thunderbird: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Mozilla Firefox ESR, Mozilla Firefox und Thunderbird ausnutzen, um beliebigen Programmcode auszuführen, Berechtigungen zu erweitern, Sicherheitsmaßnahmen zu umgehen, Daten offenzulegen oder zu manipulieren, einen Denial-of-Service-Zustand auszulösen oder andere, nicht näher spezifizierte Angriffe zu starten.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1240Multiples vulnérabilités dans les produits Mozilla

814 Référence CVE CVE-2026-100815 https://www.cve.org/CVERecord?id=CVE-2026-100815 Référence CVE CVE-2026-100816 https://www.cve.org/CVERecord?id=CVE-2026-100816 Référence CVE CVE-2026-100817 https://www.cve.org/CVERecord?id=CVE-2026-100817 Référence CVE CVE-2026-100818 https://www.cve.org/CVERecord?id=CVE-2026-100818 Référence CVE CVE-2026-100819 https://www.cve.org/CVERecord?id=CVE-2026-100819 Référence CVE CVE-2026-100820 https://www.cve.org/CVERecord?id=CVE-2026-100820 Référence CVE CVE-2026-100821 https://www.cve.org/CVERecord?id=CVE-2026-100821 Référence CVE CVE-2026-100822 https://www.cve.org/CVERecord?id=CVE-2026-100822 Référence CVE CVE-2026-100823 https://www.cve.org/CVERecord?id=CVE-2026-100823 Référence CVE CVE-2026-100824 https://www.cve.org/CVERecord?id=CVE-2026-100824 Référence CVE CVE-2026-100825 https://www.cve.org/CVERecord?id=CVE-2026-100825 Référence CVE CVE-2026-100826 https://www.cve.org/CVERecord?id=CVE-2026-100826 Référence CVE CVE-2026-100828 https://www.cve.org/CVERecord?id=CVE-2026-100828 Référence CVE CVE-2026-100829 https://www.cve.org/CVERecord?id=CVE-2026-100829 Référence CVE CVE-2026-100830 https://www.cve.org/CVERecord?id=CVE-2026-100830 Référence CVE CVE-2026-100831 https://www.cve.org/CVERecord?id=CVE-2026-100831 Référence CVE CVE-2026-100832 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.
Fix availability varies by product
Affected
Fixed
Firefox: 157 ≤ *
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 articles1 stored document

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 157 — Mozilla →Original publisher ↗Searchable text snapshot · Captured 29 Sep 2026Security Vulnerabilities fixed in Firefox 157 Announced September 29, 2026 Impact high Products Firefox Fixed in Firefox 157 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
04

Evidence and provenance

Published 29 Sept 2026 · Last source change 1 Oct 2026, 10:50 UTC · CWE-451 · User Interface (UI) Misrepresentation of Critical Information

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 2026-09-30
European sourceENISA EUVD · EUVD-2026-88802
Product sourceVendor CSAF · SUSE Product Security Team
Remediation sourceCVE/CNA references
CWE sourceCISA ADP
NVD statusNVD enriched

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 mitigation: bugzilla.mozilla.org/show_bug.cgi?id=2054384; added vendor advisory: mozilla.org/mfsa2026-97.
    Before
    remediation: bugzilla.mozilla.org/show_bug.cgi?id=2054384
    After
    mitigation: bugzilla.mozilla.org/show_bug.cgi?id=2054384 · remediation: bugzilla.mozilla.org/show_bug.cgi?id=2054384 · vendor advisory: mozilla.org/mfsa2026-97
    security@mozilla.org ↗
  2. Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.
    Before
    No public exploit
    After
    Public exploit reference
    security@mozilla.org ↗
  3. SeveritySeverity changed from Unknown to Medium.
    Before
    Unknown
    After
    Medium
    CISA ADP ↗
  4. CVSS scoreCVSS score changed from not recorded to 5.4 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L).
    Before
    not recorded
    After
    5.4 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L)
    CISA ADP ↗
  5. ENISA EUVD mappingEUVD-2026-88802 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-88802"}
    ENISA EUVD ↗
  6. Vendor guidanceAuthoritative vendor guidance changed: added remediation: bugzilla.mozilla.org/show_bug.cgi?id=2054384; removed patch: mozilla.org/mfsa2026-97; removed remediation: mozilla.org/mfsa2026-97.
    Before
    patch: mozilla.org/mfsa2026-97 · remediation: mozilla.org/mfsa2026-97
    After
    remediation: bugzilla.mozilla.org/show_bug.cgi?id=2054384
    CNA ↗
  7. Affected versionsThe structured affected or fixed version information changed.
    Before
    See the linked Mozilla advisory for the product-specific affected versions. · Fixed: Firefox 157
    After
    See the vendor and CVE records for the affected range. · Fixed: Firefox: 157 ≤ *
    CNA ↗
  8. SeveritySeverity changed from Low to Unknown.
    Before
    Low
    After
    Unknown
    CVE.org ↗
  9. Catalogue recordCVE added to the BlackTree catalogue.
    Authoritative vendor security advisory ↗
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-2026-88802↗Vendor CSAF · SUSE Product Security Team↗Public exploit reference↗Vendor advisory↗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-2026-100823 · cve.blacktree.nl