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FirefoxWeb browser · Mozilla

CVE-2012-3963

HIGH · 10.0 CVSS v2.0 Published 2012-08-29
Fix available
A fix is available. Upgrade to 2.12 / 10.0.7 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
Use-after-free vulnerability in the js::gc::MapAllocToTraceKind function in Mozilla Firefox before 15.0, Firefox ESR 10.x before 10.0.7, Thunderbird before 15.0, Thunderbird ESR 10.x before 10.0.7, and SeaMonkey before 2.12 allows remote attackers to execute arbitrary code via unspecified vectors.

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 confidence

Use-after-free vulnerability in the js::gc::MapAllocToTraceKind function of Mozilla's JavaScript garbage collection subsystem allows remote attackers to execute arbitrary code by freeing memory that is still being accessed.

MitigationUpdate affected Mozilla products to patched versions: Firefox 15.0+, Firefox ESR 10.0.7+, Thunderbird 15.0+, Thunderbird ESR 10.0.7+, or SeaMonkey 2.12+. Apply via vendor auto-update or manual installation.

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
Affected:< 15.0>= 10.0, < 10.0.7
Enterprise Linux DesktopOperating system
Affected:= 5.0= 6.0
Enterprise Linux EusOperating system
Affected:= 6.3
Enterprise Linux ServerOperating system
Affected:= 5.0= 6.0
Enterprise Linux Server EusOperating system
Affected:= 6.3
Enterprise Linux WorkstationOperating system
Affected:= 5.0= 6.0
Ubuntu LinuxOperating system
Affected:= 10.04= 11.04= 11.10= 12.04
SeamonkeyApplication
Affected:< 2.12

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Firefox version
    Open Firefox, go to Help > About Firefox, or run: firefox --version
    Affected if Version is below 10.0, OR between 10.0 and 10.0.7 (excluding 10.0.7), OR between 10.0.7 and 15.0 (excluding 15.0)
  2. Identify installed SeaMonkey version
    Open SeaMonkey, go to Help > About SeaMonkey, or run: seamonkey --version
    Affected if Version is below 2.12 (any 2.x version below 2.12)
  3. Check if JavaScript is enabled in the browser
    In Firefox/SeaMonkey, go to Options/Preferences > Content and verify 'Enable JavaScript' is checked. This is the default setting.
    Affected if JavaScript is enabled (default state). The vulnerability exists in the JS garbage collector and triggers when JavaScript executes.
  4. Check OS-level browser packages on RHEL/CentOS
    Run: rpm -qa | grep -E 'firefox|seamonkey' to list installed Mozilla browser packages and their versions
    Affected if Any Firefox or SeaMonkey package version matches the affected version ranges for the OS (5.0, 6.0, 6.3 for RHEL variants)
  5. Check OS-level browser packages on Ubuntu/Debian
    Run: dpkg -l | grep -E 'firefox|seamonkey' or check Software Center for installed Mozilla browser packages
    Affected if Any Firefox or SeaMonkey package version matches the affected version ranges for Ubuntu (10.04, 11.04, 11.10, 12.04)

Your environment is affected if you are running Firefox below 15.0 (excluding 10.0.7 and ESR 10.0.7+), or SeaMonkey below 2.12, with JavaScript enabled (the default).

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to 2.12 / 10.0.7 / 15.0 or later
Fixed in 2.1210.0.715.0
Interim mitigation

Update affected Mozilla products to patched versions: Firefox 15.0+, Firefox ESR 10.0.7+, Thunderbird 15.0+, Thunderbird ESR 10.0.7+, or SeaMonkey 2.12+. Apply via vendor auto-update or manual installation.

Recommended fix High confidence

Firefox 15.0, Firefox ESR 10.0.7, Thunderbird 15.0, Thunderbird ESR 10.0.7, or SeaMonkey 2.12

  1. Identify which Mozilla product is installed: Firefox, Firefox ESR, Thunderbird, Thunderbird ESR, or SeaMonkey
  2. Check the current installed version using the system's package manager (e.g., rpm -q firefox, dpkg -l firefox, or yum info firefox)
  3. For Fedora/Red Hat Enterprise Linux systems: Run 'yum update firefox' or 'yum update thunderbird' or 'yum update seamonkey' to install the patched version
  4. For Ubuntu/Debian systems: Run 'apt-get update && apt-get install firefox' (or thunderbird/seamonkey) to get the latest available fixed version
  5. Restart the browser or email client after the update completes
  6. Verify the installed version matches or exceeds the fixed release: Firefox 15.0+, Firefox ESR 10.0.7+, Thunderbird 15.0+, Thunderbird ESR 10.0.7+, or SeaMonkey 2.12+
Caveat Major version upgrades (e.g., Firefox 10.x to 15.x) may cause compatibility issues with existing extensions or plugins; test in a non-production environment first if possible

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
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2012-3963 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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