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FirefoxWeb browser · Mozilla

CVE-2012-3959

HIGH · 10.0 CVSS v2.0 Published 2012-08-29
Fix available
A fix is available. Upgrade to 10.0.7 / 15.0 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 nsRangeUpdater::SelAdjDeleteNode 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 or cause a denial of service (heap memory corruption) 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 Mozilla Firefox, Thunderbird, SeaMonkey, and their ESR versions allows remote attackers to execute arbitrary code or cause heap memory corruption via memory corruption in the nsRangeUpdater::SelAdjDeleteNode function when handling unspecified DOM manipulation vectors.

MitigationUpgrade to Firefox 15.0+, Firefox ESR 10.0.7+, Thunderbird 15.0+, Thunderbird ESR 10.0.7+, or SeaMonkey 2.12+ to patch the use-after-free in nsRangeUpdater::SelAdjDeleteNode.

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
Debian LinuxOperating system
Affected:= 6.0= 7.0

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 Mozilla products
    Check for Firefox, Thunderbird, or SeaMonkey on the system. On Linux, run: dpkg -l | grep -E 'firefox|thunderbird|seamonkey' or rpm -qa | grep -E 'firefox|thunderbird|seamonkey'. On Windows, check Program Files for Mozilla folders. On macOS, check /Applications for these applications.
    Affected if None of these products are installed (not affected); if any are present, continue to version check.
  2. Determine Firefox version
    Run 'firefox --version' from command line, or open Firefox and navigate to Help > About Firefox. Record the version number displayed (e.g., 10.0.6, 14.0.1).
    Affected if Version is below 15.0, OR version is 10.0.x where x is less than 7 (10.0.0 through 10.0.6). Example: 10.0.6 is affected, 10.0.7 is not, 15.0 is not.
  3. Determine Thunderbird version
    Run 'thunderbird --version' from command line, or open Thunderbird and navigate to Help > About Thunderbird. Record the version number displayed.
    Affected if Version is below 15.0, OR version is 10.0.x where x is less than 7 (10.0.0 through 10.0.6). Example: 10.0.6 is affected, 10.0.7 is not, 15.0 is not.
  4. Determine SeaMonkey version
    Run 'seamonkey --version' from command line, or open SeaMonkey and navigate to Help > About SeaMonkey. Record the version number displayed.
    Affected if Version is below 2.12 (any 2.x version where x < 12, or any 1.x version). Example: 2.11 is affected, 2.12 is not.

The user is affected if they have Firefox < 15.0 (or 10.0.x below 10.0.7), Thunderbird < 15.0 (or 10.0.x below 10.0.7), or SeaMonkey < 2.12 installed.

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 10.0.7 / 15.0 or later
Fixed in 10.0.715.0
Interim mitigation

Upgrade to Firefox 15.0+, Firefox ESR 10.0.7+, Thunderbird 15.0+, Thunderbird ESR 10.0.7+, or SeaMonkey 2.12+ to patch the use-after-free in nsRangeUpdater::SelAdjDeleteNode.

Recommended fix High confidence

Firefox 15.0+ (or Firefox ESR 10.0.7+)

  1. Back up all critical data and bookmarks before proceeding
  2. Close all instances of Firefox, Thunderbird, or SeaMonkey running on the system
  3. For Debian/Ubuntu systems: Run 'apt-get update && apt-get upgrade' to install available security updates
  4. For RHEL/CentOS systems: Run 'yum update' or 'yum update firefox' to apply available security patches
  5. For openSUSE systems: Run 'zypper update' to apply available security patches
  6. Alternatively, download Firefox 15.0 or later from the official Mozilla website (mozilla.org)
  7. Install the updated package or run the downloaded installer
  8. Restart the application and verify the version by navigating to Help > About
Caveat Upgrading to a newer major version may change UI behavior, disable legacy add-ons, or affect existing profiles; 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
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
Get the upgrade done

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Scan for this in your stack

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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-2012-3959 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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