FirefoxWeb browser · Mozilla
CVE-2026-4715
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 · uneditedUninitialized memory in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
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 confidenceUninitialized memory vulnerability in the Graphics: Canvas2D component of Firefox and Thunderbird allows potential code execution or sensitive information disclosure through improper memory handling during canvas rendering operations.
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
< 140.9.0< 149.0CVSS 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
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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 checksWork through these to decide whether this CVE applies to you.
-
Determine if Firefox is installedOpen Firefox, click the menu (three lines) > Help > About Firefox, or enter 'about:support' in the address barAffected if Firefox version is displayed as below 140.9.0 or between 140.9.0 and 148.x inclusive (any version < 149.0)
-
Determine if Thunderbird is installedOpen Thunderbird, click the menu > Help > About ThunderbirdAffected if Thunderbird version is displayed as below 140.9.0 or between 140.9.0 and 148.x inclusive (any version < 149.0)
-
Verify Canvas2D usage (optional context)Canvas2D is a standard graphics feature used by web content; any user who renders HTML5 canvas content in Firefox or Thunderbird could trigger the vulnerable code pathAffected if The application processes canvas rendering operations from web content or email content containing canvas elements
You are affected if either Firefox or Thunderbird is installed with any version below 140.9.0, or any version from 140.9.0 through 148.x, since the vulnerability exists in the Canvas2D graphics component.
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 · scoped140.9.0149.0
Update vulnerable installations to Firefox 149+, Firefox ESR 140.9+, Thunderbird 149+, or Thunderbird 140.9+ to remediate this uninitialized memory issue.
Firefox 149 (regular) or Firefox ESR 140.9 (ESR)
- Check current Firefox version by navigating to Help > About Firefox
- If running Firefox regular release: download and install Firefox 149 or later from www.mozilla.org
- If running Firefox ESR: download and install Firefox ESR 140.9 or later from www.mozilla.org
- Restart the browser after installation
- Verify the update was successful by checking Help > About Firefox shows version 149.x or ESR 140.9.x
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 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 $1,696.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-4715 — 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-2026-4715 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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