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CVE-2026-6781 Mozilla CVE debrief

Mozilla Firefox and Thunderbird have a vulnerability that can cause a denial-of-service in the Audio/Video: Playback component. This issue was fixed in Firefox 150 and Thunderbird 150. The vulnerability, tracked as CVE-2026-6781, has a CVSS score of 7.5, indicating high severity. Defenders and IT teams should assess exposure and apply patches to prevent potential service disruptions. The vulnerability affects the Audio/Video: Playback component, which is commonly used in various environments.

Vendor
Mozilla
Product
Firefox
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-04-21
Original CVE updated
2026-10-26
Advisory published
2026-04-21
Advisory updated
2026-10-26

Who should care

Defenders and IT teams responsible for managing Mozilla Firefox and Thunderbird installations, especially in environments where the Audio/Video: Playback component is used, should assess exposure and apply patches.

Why it matters

CVE-2026-6781 is a high-severity denial-of-service vulnerability in Mozilla Firefox and Thunderbird's Audio/Video: Playback component. Defenders should prioritize verifying exposure and applying patches to prevent potential service disruptions.

  • Potential denial-of-service attacks against unpatched Firefox and Thunderbird installations
  • Need to verify exposure and apply patches in environments using the Audio/Video: Playback component
  • Possible service disruptions if the vulnerability is exploited

Technical summary

The vulnerability, CVE-2026-6781, causes a denial-of-service in the Audio/Video: Playback component of Mozilla Firefox and Thunderbird. It was fixed in Firefox 150 and Thunderbird 150. The CVSS score is 7.5, indicating a high severity. This vulnerability can be exploited through maliciously crafted audio or video content, potentially leading to service disruptions. Defenders should prioritize verifying exposure and applying patches for Firefox and Thunderbird, especially in environments where the Audio/Video: Playback component is used.

Defensive priority

Defenders should prioritize verifying exposure and applying patches for Firefox and Thunderbird, especially in environments where the Audio/Video: Playback component is used.

Recommended defensive actions

  • Verify and apply patches for Firefox and Thunderbird
  • Assess exposure in environments using the Audio/Video: Playback component
  • Monitor for potential denial-of-service attacks

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, its impact, and fixed versions. Vendor advisories from Mozilla offer additional context.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-6781 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-6781

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

  • CVE-2026-6781 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-6781

    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.