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CVE-2026-92043 Mozilla CVE debrief

Mozilla Firefox and Thunderbird users should assess exposure to CVE-2026-92043, a high-severity privilege escalation vulnerability due to incorrect boundary conditions in the Audio/Video component. Defenders should verify if their deployments use vulnerable versions and prioritize patching or mitigating affected systems. This vulnerability, with a CVSS score of 8.8, was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3. Users should review compensating controls and monitor for potential exploitation attempts.

Vendor
Mozilla
Product
Firefox
CVSS
HIGH 8.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-15
Original CVE updated
2026-10-05
Advisory published
2026-09-15
Advisory updated
2026-10-05

Who should care

Defenders and IT teams responsible for Mozilla Firefox and Thunderbird deployments should assess exposure and prioritize patching or mitigating affected systems to prevent potential privilege escalation attacks.

Why it matters

CVE-2026-92043 is a high-severity privilege escalation vulnerability in Mozilla Firefox and Thunderbird. Defenders should assess exposure, prioritize patching or mitigation, and implement compensating controls to prevent potential exploitation.

  • Verify and patch vulnerable Firefox, Firefox ESR, and Thunderbird versions to prevent exploitation
  • Assess exposure of Mozilla Firefox and Thunderbird deployments to prioritize patching or mitigation efforts
  • Implement compensating controls, such as restricting access to sensitive components, until patches are applied
  • Monitor for potential exploitation attempts targeting CVE-2026-92043

Technical summary

CVE-2026-92043 is a high-severity vulnerability in Mozilla Firefox and Thunderbird due to incorrect boundary conditions in the Audio/Video component, allowing for privilege escalation. The vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3. Defenders should assess exposure, prioritize patching or mitigation, and implement compensating controls to prevent potential exploitation. The CVE record and NVD entry provide details on the vulnerability, including its high CVSS score of 8.8 and affected software versions.

Defensive priority

Patch or verify exposure for Firefox, Firefox ESR, Thunderbird versions before fixed releases

Recommended defensive actions

  • Patch Firefox to version 156 or later
  • Patch Thunderbird to version 156 or later
  • Patch Firefox ESR to version 153.3 or later
  • Verify and update Thunderbird to version 153.3 or later
  • Inventory and assess exposure of Mozilla Firefox and Thunderbird deployments

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its high CVSS score of 8.8 and affected software versions. Vendor advisories from Mozilla offer guidance on patched versions.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-92043 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-92043

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-92043 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-92043

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.