FirefoxWeb browser · Mozilla
CVE-2016-1968
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 · uneditedInteger underflow in Brotli, as used in Mozilla Firefox before 45.0, allows remote attackers to execute arbitrary code or cause a denial of service (buffer overflow) via crafted data with brotli compression.
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 confidenceAn integer underflow vulnerability exists in the Brotli decompression library used in Mozilla Firefox versions prior to 45.0. When processing specially crafted brotli-compressed data, the integer underflow causes a buffer overflow that can be exploited for arbitrary code execution or denial of service.
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
<= 44.0.2CVSS 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:3.0/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 checksWork through these to decide whether this CVE applies to you.
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Check Firefox version via command lineRun 'firefox --version' on Linux/Mac, or '"C:\Program Files\Mozilla Firefox\firefox.exe" -v' on Windows via command promptAffected if Version number returned is 44.0.2 or lower
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Check Firefox version in browser UIOpen Firefox, click the menu button (three horizontal lines), select Help, then About Firefox. The version number is displayed on that pageAffected if Displayed version is 44.0.2 or lower
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Check Firefox version via package manager or registryOn Windows: open Registry Editor and navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla\Mozilla Firefox\CurrentVersion. On Linux: check your package manager (dpkg -l | grep firefox or rpm -q firefox)Affected if The version value found is 44.0.2 or lower
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Confirm Brotli decompression support is presentThe vulnerability exists in the brotli library integrated into Firefox. This library is present in affected versions. No separate check needed beyond version verificationAffected if Firefox version is 44.0.2 or lower (the Brotli library with the flaw is included in these versions)
User is affected if their installed Firefox version is 44.0.2 or any version prior to 45.0, as the vulnerable Brotli decompression library is present in 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.
From vendor dataUpgrade Mozilla Firefox to version 45.0 or later to remediate this vulnerability. Apply via standard software update mechanisms or enterprise patch management.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 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 $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-1968 — 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-2016-1968 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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