PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-8091 Mozilla CVE debrief

CVE-2026-8091 is a critical vulnerability in Mozilla Firefox and Thunderbird, with a CVSS score of 9.8. The vulnerability is caused by incorrect boundary conditions in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, Thunderbird 140.10.1, and Firefox ESR 115.35.2. The vulnerability was published on May 7, 2026, and modified on June 30, 2026. The CVE record and NVD detail provide more information about the vulnerability.

Vendor
Mozilla
Product
Firefox
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-07
Original CVE updated
2026-08-11
Advisory published
2026-05-07
Advisory updated
2026-08-11

Who should care

Organizations and individuals using Mozilla Firefox and Thunderbird should be aware of this critical vulnerability and apply the necessary patches to prevent exploitation. The vulnerability has a high impact on confidentiality, integrity, and availability. Users of affected products should prioritize patching to mitigate potential risks.

Technical summary

The vulnerability is caused by incorrect boundary conditions in the Audio/Video: Playback component of Mozilla Firefox and Thunderbird. This could allow an attacker to execute arbitrary code on the affected system. The vulnerability has a CVSS score of 9.8, indicating a critical severity level. The CVE record and NVD detail provide more information about the vulnerability, including affected products and versions.

Defensive priority

High priority should be given to patching affected systems, as the vulnerability has a critical severity level and could allow an attacker to execute arbitrary code. Organizations should prioritize patching to mitigate potential risks.

Recommended defensive actions

  • Apply patches for Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, Thunderbird 140.10.1, and Firefox ESR 115.35.2.
  • Review and update inventory of affected products and versions.
  • Monitor system logs for potential exploitation attempts.
  • Implement compensating controls, such as network segmentation and access controls.
  • Verify that all necessary patches have been applied and systems are up-to-date.

Evidence notes

The CVE record and NVD detail provide more information about the vulnerability, including affected products and versions. The vulnerability was published on May 7, 2026, and modified on June 30, 2026. The source item URL provides additional information about the vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-8091 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-8091

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

  • CVE-2026-8091 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-8091

    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.