FirefoxWeb browser · Mozilla
CVE-2012-3973
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 debugger in the developer-tools subsystem in Mozilla Firefox before 15.0, when remote debugging is disabled, does not properly restrict access to the remote-debugging service, which allows remote attackers to execute arbitrary code by leveraging the presence of the HTTPMonitor extension and connecting to that service through the HTTPMonitor port.
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 confidenceMozilla Firefox before 15.0 contains a security bypass in its developer-tools debugger subsystem. When remote debugging is disabled, the debugger improperly restricts access to the remote-debugging service. An attacker with the HTTPMonitor extension present and the ability to connect to the HTTPMonitor port can exploit this to execute arbitrary code.
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
<= 14.0= 1.0= 1.0.1= 1.0.2= 1.0.3= 1.0.4= 1.0.5= 1.0.6= 1.0.7= 1.0.8= 1.4.1= 1.5CVSS 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
- Authentication
- None
- Confidentiality
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:N/AC:H/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, click Help > About Firefox, or navigate to about:support in the address bar to view the installed version numberAffected if The installed version is 14.0 or earlier, or is one of these specific versions: 1.0, 1.0.1, 1.0.2, 1.0.3, 1.0.4, 1.0.5, 1.0.6, 1.0.7, 1.0.8, 1.4.1, or 1.5
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Check for HTTPMonitor extensionNavigate to about:support in Firefox, scroll to the Extensions section, or check the profile directory for a folder named HTTPMonitorAffected if The HTTPMonitor extension is listed as installed in the browser extensions
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Verify remote debugging statusOpen Firefox developer tools (F12 or Ctrl+Shift+I), access Settings, and look under Developer Tools for Remote Debugging settingsAffected if Remote debugging is enabled, or the debugger settings show non-default configuration allowing remote connections
A user is affected if their Firefox version is 14.0 or earlier (including specific older versions) AND the HTTPMonitor extension is installed, regardless of remote debugging being enabled or disabled.
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 to Firefox 15.0 or later. Remove the HTTPMonitor extension if not required, and ensure remote debugging settings are properly configured.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 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 $1,456.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2012-3973 — 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-2012-3973 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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