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FirefoxWeb browser · Mozilla

CVE-2026-8968

HIGH · 7.5 CVSS v3.1 Published 2026-05-19
Fix available
A fix is available. Upgrade to 140.11 / 140.11.0 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Denial-of-service due to invalid pointer in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A denial-of-service vulnerability exists in the Web Codecs component (handling audio/video processing) due to an invalid pointer dereference. This could cause the browser or Thunderbird to crash when processing specially crafted media content.

MitigationUpdate affected installations to Firefox 151+, Firefox ESR 140.11+, Thunderbird 151+, or Thunderbird 140.11+ to obtain the patched version of the Web Codecs component.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FirefoxWeb browser
Affected:< 140.11.0< 151.0.0
ThunderbirdApplication
Affected:< 140.11< 151.0.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Firefox version
    Navigate to Help > About Firefox, or run 'firefox --version' from command line, or check the application log/executable properties
    Affected if Version is below 140.11.0 OR between 140.11.0 and 151.0.0 (exclusive of 151.0.0)
  2. Check installed Thunderbird version
    Navigate to Help > About Thunderbird, or run 'thunderbird --version' from command line
    Affected if Version is below 140.11 OR between 140.11 and 151.0.0 (exclusive of 151.0.0)
  3. Verify Web Codecs API is enabled
    Open about:config in the browser address bar, search for 'media.webcodecs.enabled', and check if the value is set to true
    Affected if The media.webcodecs.enabled preference is set to true (default varies by version)
  4. Check for WebCodecs API usage in extensions or web content
    Review browser extension permissions and any local web content that may invoke navigator.mediaDevices.getFrameData() or similar Web Codecs API methods
    Affected if Extensions or web pages actively use the Web Codecs API to process audio or video data

You are affected if your Firefox or Thunderbird version is below 151.0.0 (or below 140.11.0 for the 140.x ESR branch) AND the Web Codecs API is enabled and being used to process untrusted media content.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 140.11 / 140.11.0 / 151.0.0 or later
Fixed in 140.11140.11.0151.0.0
Interim mitigation

Update affected installations to Firefox 151+, Firefox ESR 140.11+, Thunderbird 151+, or Thunderbird 140.11+ to obtain the patched version of the Web Codecs component.

Recommended fix High confidence

Firefox 151 / Firefox ESR 140.11 / Thunderbird 151 / Thunderbird 140.11

  1. For Firefox users: Open Firefox, go to Menu > Help > About Firefox, and click 'Check for updates' to download and install version 151 (or ESR 140.11 for enterprise environments)
  2. For Thunderbird users: Open Thunderbird, go to Menu > Help > About Thunderbird, and click 'Check for updates' to download and install version 151 (or version 140.11 for enterprise environments)
  3. Alternatively, download the latest versions directly from https://www.mozilla.org/firefox/download/ or https://www.mozilla.org/thunderbird/download/
  4. After installation, restart the application to complete the update
Caveat Mozilla stable releases typically have minimal breaking changes; however, some older extensions or website features may not be compatible with major version upgrades

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-8968 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data