FirefoxWeb browser · Mozilla
CVE-2026-2789
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 · uneditedUse-after-free in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
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 confidenceUse-after-free vulnerability in the ImageLib graphics component allows memory corruption through continued access to freed memory, potentially enabling arbitrary code execution.
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
< 115.33.0< 148.0>= 128.0, < 140.8.0< 140.8.0< 148.0CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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 checksWork through these to decide whether this CVE applies to you.
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Check installed Firefox versionNavigate to about:Firefox in Firefox browser, or run 'firefox --version' from command line, or check the application package/version information in your OS (e.g., Add/Remove Programs on Windows, dmg pkg info on macOS, dpkg/rpm on Linux)Affected if Version is below 115.33.0, or between 128.0.0 and 140.7.x inclusive, or below 148.0 (when 115.33.0 or 140.8.0 are not reached)
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Check installed Thunderbird versionNavigate to about:Thunderbird in Thunderbird, or run 'thunderbird --version' from command line, or check the application package/version information in your OSAffected if Version is below 140.8.0 or below 148.0 (when 140.8.0 is not reached)
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Confirm ImageLib component is in useImageLib is used when Firefox or Thunderbird processes images (PNG, JPEG, GIF, WebP, etc.) - load or view any image in the browser email client to trigger the vulnerable code pathAffected if The application processes image content; the use-after-free occurs during image handling operations
You are affected if you run Firefox version < 115.33.0, or any version from 128.x through 140.7.x, or < 148.0 without having updated to 115.33/140.8; or Thunderbird version < 140.8.0 or < 148.0 without the 140.8 update.
Generated from the published advisory. Verify against your own configuration.
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 · scoped115.33.0140.8.0148.0
Update affected products to Firefox 148, Firefox ESR 115.33/140.8, Thunderbird 148/140.8, or later versions.
Firefox 148+ / Firefox ESR 115.33+ / Firefox ESR 140.8+ / Thunderbird 140.8+ (depending on your release branch)
- 1. Determine which Firefox or Thunderbird branch you are using (main release, ESR 115.x, or ESR 140.x)
- 2. For Firefox main releases: upgrade to version 148 or later
- 3. For Firefox ESR 115.x: upgrade to version 115.33 or later
- 4. For Firefox ESR 140.x: upgrade to version 140.8 or later
- 5. For Thunderbird: upgrade to version 140.8 or later (or version 148)
- 6. After upgrade, verify the installed version matches the fixed release
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
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-2789 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-2789 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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