FirefoxWeb browser · Mozilla
CVE-2016-2808
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 · uneditedThe watch implementation in the JavaScript engine in Mozilla Firefox before 46.0, Firefox ESR 38.x before 38.8, and Firefox ESR 45.x before 45.1 allows remote attackers to execute arbitrary code or cause a denial of service (generation-count overflow, out-of-bounds HashMap write access, and application crash) via a crafted web site.
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 confidenceA memory corruption vulnerability exists in the JavaScript engine's watch implementation in Mozilla Firefox prior to versions 46.0, ESR 38.8, and ESR 45.1. The vulnerability involves a generation-count overflow leading to out-of-bounds HashMap write access, which can be triggered remotely via crafted JavaScript on a malicious website to achieve arbitrary code execution or cause a crash.
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
<= 45.0.2= 38.0= 38.0.1= 38.0.5= 38.1.0= 38.1.1= 38.2.0= 38.2.1= 38.3.0= 38.4.0= 38.5.0= 38.5.1CVSS 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
- High
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.0/AV:N/AC:H/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 installed Firefox versionOpen about:support in Firefox address bar, or run 'firefox --version' from command line, or check Help > About FirefoxAffected if Version is 45.0.2 or lower, or matches any of these: 38.0, 38.0.1, 38.0.5, 38.1.0, 38.1.1, 38.2.0, 38.2.1, 38.3.0, 38.4.0, 38.5.0, 38.5.1
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Confirm version is in vulnerable rangeCompare your installed version against the affected list: versions <=45.0.2 and specific 38.x releases (38.0 through 38.5.1)Affected if Your version matches any affected version listed in the CVE
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Identify if JavaScript watch() is in useReview browser extensions, bookmarks with JavaScript, or saved web pages that may contain JavaScript using the Object.watch() methodAffected if You have extensions or saved content using the watch() method on objects, which is the vulnerable code path
You are affected if Firefox version is 45.0.2 or lower, or matches any 38.x variant from 38.0 to 38.5.1, and the browser executes JavaScript with the watch() method.
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 Firefox to version 46.0 or later (or ESR 38.8+/45.1+) to patch the vulnerable JavaScript engine watch implementation. In enterprise environments, deploy the update via standard software distribution mechanisms.
Fix this in Firefox
Scoped from the published advisory
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 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 $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-2808 — 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-2016-2808 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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