FirefoxWeb browser · Mozilla
CVE-2026-6783
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 · uneditedIncorrect boundary conditions, integer overflow in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.
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 confidenceInteger overflow due to incorrect boundary conditions in the Audio/Video Playback component of Firefox and Thunderbird. This memory corruption vulnerability could allow an attacker to cause undefined behavior or potentially execute arbitrary code through specially crafted media content.
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
< 150.0< 150.0CVSS 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
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
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.
-
Check Firefox versionOpen Firefox, navigate to Menu > Help > About Firefox, or run 'firefox --version' from command lineAffected if The displayed version is below 150.0 (e.g., 149.x, 148.x, etc.)
-
Check Thunderbird versionOpen Thunderbird, navigate to Menu > Help > About Thunderbird, or run 'thunderbird --version' from command lineAffected if The displayed version is below 150.0 (e.g., 149.x, 148.x, etc.)
You are affected if either Firefox or Thunderbird is installed with a version lower than 150.0, as the integer overflow vulnerability exists in the Audio/Video Playback component of those versions.
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 · scoped150.0
Update Firefox and Thunderbird to version 150 or later to obtain the patched version of the Audio/Video Playback component.
Firefox 150 and Thunderbird 150 (or later)
- 1. Check current Firefox or Thunderbird version by navigating to Menu > Help > About (or typing 'about:support' in the address bar)
- 2. Download Firefox 150 or later from the official Mozilla website: https://www.mozilla.org/firefox/releases/
- 3. Download Thunderbird 150 or later from the official Mozilla website: https://www.thunderbird.net/releases/
- 4. Run the installer and follow the prompts to complete the upgrade, or enable automatic updates in the application settings
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 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 $1,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-6783 — 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-2026-6783 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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- 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
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