FirefoxWeb browser · Mozilla
CVE-2015-7220
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 · uneditedBuffer overflow in the XDRBuffer::grow function in js/src/vm/Xdr.cpp in Mozilla Firefox before 43.0 might allow remote attackers to cause a denial of service or possibly have unspecified other impact via crafted JavaScript code.
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 confidenceBuffer overflow vulnerability in the XDRBuffer::grow function in Mozilla Firefox's JavaScript engine (SpiderMonkey) before version 43.0. The XDR (External Data Representation) buffer handling code fails to properly validate buffer growth, allowing crafted JavaScript code to overflow the buffer and potentially execute arbitrary code or cause 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
<= 42.0
FedoraOperating system
= 22= 23= 42.1= 13.1= 13.2CVSS 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
- Authentication
- None
- Confidentiality
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:N/AC:L/Au:N/C:C/I:C/A:C
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 versionOpen Firefox, go to Help > About Firefox, or run 'firefox --version' from command lineAffected if The displayed version is 42.0 or lower
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Check SpiderMonkey library version on LinuxRun 'rpm -q firefox' (Fedora) or 'zypper se MozillaFirefox' (openSUSE) to query the installed Firefox package versionAffected if The Firefox package version corresponds to 42.0 or earlier (e.g., 42.0, 41.x, 40.x)
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Check for SpiderMonkey XDR supportExamine if the JavaScript engine can be invoked via 'js' command or check for libmozjs library files in /usr/lib/ (Linux systems)Affected if The SpiderMonkey library version matches the Firefox 42.0 or earlier baseline, indicating the unpatched XDRBuffer::grow function is present
A user is affected if their installed Firefox version is 42.0 or earlier, or if the bundled SpiderMonkey library version corresponds to an unpatched release.
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 · scopedUpdate Mozilla Firefox to version 43.0 or later to obtain the patched version of the JavaScript engine that properly validates XDR buffer allocations.
Firefox 43.0 or later
- Check the current Firefox version by navigating to Help > About Firefox
- Download Firefox 43.0 or later from the official Mozilla website (www.mozilla.org)
- Close all Firefox instances
- Install the downloaded Firefox 43.0 or newer version
- Restart Firefox and verify the new version is running
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 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 $2,512.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-7220 — 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-2015-7220 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
- No spam, self-promotion, credentials, or personal data