FirefoxWeb browser · Mozilla
CVE-2016-5274
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 vulnerability in the nsFrameManager::CaptureFrameState function in Mozilla Firefox before 49.0, Firefox ESR 45.x before 45.4, and Thunderbird < 45.4 allows remote attackers to execute arbitrary code by leveraging improper interaction between restyling and the Web Animations model implementation.
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 nsFrameManager::CaptureFrameState in Firefox and Thunderbird allows remote code execution through improper interaction between restyling and the Web Animations model implementation, causing memory corruption.
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
<= 48.0.2= 45.1.0= 45.1.1= 45.2.0= 45.3.0CVSS 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:3.0/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 if Firefox is installedOpen Firefox, go to Help > About Firefox, or run 'firefox --version' from command lineAffected if Firefox is installed and the version is 45.1.0, 45.1.1, 45.2.0, 45.3.0, or any version from 45.4.0 through 48.0.2
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Confirm Firefox version numberIn Firefox, navigate to about:support or check Help > About Firefox to see the exact version stringAffected if The displayed version falls within 45.1.0 to 48.0.2 inclusive
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Check if Thunderbird is installedOpen Thunderbird, go to Help > About Thunderbird, or run 'thunderbird --version' from command lineAffected if Thunderbird shares the same Gecko engine and may be affected; compare version to Firefox equivalents (45.1.0-48.0.2 range) since the summary indicates both products are vulnerable
You are affected if you run Firefox version 45.1.0 through 48.0.2 (including 45.4.x, 46.x, 47.x versions) or Thunderbird with a comparable Gecko engine version in that range, as the use-after-free in nsFrameManager::CaptureFrameState requires the Web Animations model to be interactable through restyling operations.
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 · scopedUpgrade to Firefox 49.0+, Firefox ESR 45.4+, or Thunderbird 45.4+ to patch the vulnerability.
Firefox 49.0 (or later); Firefox ESR 45.4 (or later); Thunderbird 45.4 (or later)
- For Firefox users: Upgrade to Firefox 49.0 or later
- For Firefox ESR 45.x users: Upgrade to Firefox ESR 45.4 or later
- For Thunderbird users: Upgrade to Thunderbird 45.4 or later
- Verify the upgrade by checking Help > About Firefox or Help > About Thunderbird
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-5274 — 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-2016-5274 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
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