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FirefoxWeb browser · Mozilla

CVE-2026-2447

HIGH · 8.8 CVSS v3.1 Published 2026-02-16
Fix available
A fix is available. Upgrade to 115.32.1 / 140.7.1 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

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
Heap buffer overflow in libvpx. This vulnerability was fixed in Firefox 147.0.4, Firefox ESR 140.7.1, Firefox ESR 115.32.1, Thunderbird 140.7.2, and Thunderbird 147.0.2.

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 · moderate confidence

Heap buffer overflow vulnerability in libvpx, the VP8/VP9 video codec library used by Firefox and Thunderbird. This memory corruption flaw allows writes beyond allocated heap buffers during video decoding, potentially enabling arbitrary code execution via specially crafted video content.

MitigationUpdate affected Mozilla products to Firefox 147.0.4+, Firefox ESR 140.7.1+/115.32.1+, or Thunderbird 140.7.2+/147.0.2+. For projects embedding libvpx directly, update to the patched libvpx version used in these releases.

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:< 115.32.1< 147.0.4>= 116.0, < 140.7.1
ThunderbirdApplication
Affected:< 140.7.2>= 141.0, < 147.0.2

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
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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. Identify installed Mozilla products
    Check if Firefox or Thunderbird is installed on the system. On Windows, look in Program Files/Firefox or Program Files/Mozilla Thunderbird. On macOS, check /Applications/Firefox.app or /Applications/Thunderbird.app. On Linux, run 'which firefox' or 'which thunderbird' in terminal.
    Affected if Either Firefox or Thunderbird is installed
  2. Check Firefox version
    For Firefox: Click menu > Help > About Firefox, or in terminal run 'firefox --version' (Linux) or check the application file properties (Windows/macOS). Record the full version number (e.g., 140.0, 115.31, etc.).
    Affected if Firefox version is < 115.32.1, OR >= 116.0 and < 140.7.1, OR < 147.0.4
  3. Check Thunderbird version
    For Thunderbird: Click menu > Help > About Thunderbird, or in terminal run 'thunderbird --version' (Linux) or check the application file properties (Windows/macOS). Record the full version number.
    Affected if Thunderbird version is < 140.7.2, OR >= 141.0 and < 147.0.2
  4. Verify VP8/VP9 video processing capability
    Confirm the product is capable of processing VP8/VP9 video content. This is enabled by default in Firefox and Thunderbird when the libvpx library is present. No additional configuration check required as this is the default state.
    Affected if The vulnerable libvpx library is present and the browser/mail client can process video content (default state)

You are affected if either Firefox or Thunderbird is installed with a version number matching any of the affected ranges: Firefox < 115.32.1, >= 116.0 and < 140.7.1, or < 147.0.4; Thunderbird < 140.7.2 or >= 141.0 and < 147.0.2.

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 115.32.1 / 140.7.1 / 140.7.2 or later
Fixed in 115.32.1140.7.1140.7.2
Interim mitigation

Update affected Mozilla products to Firefox 147.0.4+, Firefox ESR 140.7.1+/115.32.1+, or Thunderbird 140.7.2+/147.0.2+. For projects embedding libvpx directly, update to the patched libvpx version used in these releases.

Recommended fix High confidence

Firefox ESR 115.32.1+ | Firefox ESR 140.7.1+ | Firefox 147.0.4+ | Thunderbird 140.7.2+ | Thunderbird 147.0.2+

  1. Identify current Firefox or Thunderbird version via Help > About (or running 'firefox --version' or 'thunderbird --version')
  2. If Firefox version is 115.x ESR: upgrade to Firefox ESR 115.32.1 or later
  3. If Firefox version is 116.0 through 140.x: upgrade to Firefox ESR 140.7.1 or later
  4. If Firefox version is 141.0 through 146.x: upgrade to Firefox 147.0.4 or later
  5. If Thunderbird version is 140.x: upgrade to Thunderbird 140.7.2 or later
  6. If Thunderbird version is 141.0 through 146.x: upgrade to Thunderbird 147.0.2 or later
  7. Restart the application after upgrade to ensure the fix is fully applied
Caveat Mozilla minor version upgrades typically have low risk; some older add-ons may be incompatible with major version jumps

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
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.

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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-2026-2447 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