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FirefoxWeb browser · Mozilla

CVE-2012-4187

HIGH · 9.3 CVSS v2.0 Published 2012-10-10
Fix available
A fix is available. Upgrade to 10.0.8 / 16.0 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
Mozilla Firefox before 16.0, Firefox ESR 10.x before 10.0.8, Thunderbird before 16.0, Thunderbird ESR 10.x before 10.0.8, and SeaMonkey before 2.13 do not properly manage a certain insPos variable, which allows remote attackers to execute arbitrary code or cause a denial of service (heap memory corruption and assertion failure) 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

A use-after-free or improper variable management vulnerability in Mozilla Firefox, Thunderbird, and SeaMonkey allows remote attackers to corrupt heap memory via improper management of the 'insPos' variable, potentially enabling arbitrary code execution.

MitigationUpgrade affected Mozilla products to Firefox 16.0+/ESR 10.0.8+, Thunderbird 16.0+/ESR 10.0.8+, or SeaMonkey 2.13+ to patch the vulnerability.

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:< 10.0.8< 16.0
Ubuntu LinuxOperating system
Affected:= 10.04= 11.04= 11.10= 12.04
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 WorkstationOperating system
Affected:= 5.0= 6.0
Thunderbird EsrApplication
Affected:< 10.0.8
ThunderbirdApplication
Affected:< 16.0

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
M
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:M/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. Determine installed Firefox version
    Run 'firefox --version' or check the package: 'rpm -q firefox' (RHEL) or 'dpkg -l firefox' (Ubuntu)
    Affected if Version is less than 10.0.8 (ESR branch) or less than 16.0 (release branch)
  2. Determine installed Thunderbird version
    Run 'thunderbird --version' or check the package: 'rpm -q thunderbird' (RHEL) or 'dpkg -l thunderbird' (Ubuntu)
    Affected if Version is less than 10.0.8 (ESR branch) or less than 16.0 (release branch)
  3. Check SeaMonkey version if installed
    Run 'seamonkey --version' or check via the application's About dialog
    Affected if Version is less than 2.13 (the fixed release for this vulnerability)

You are affected if any installed Firefox, Thunderbird, or SeaMonkey version matches the affected ranges: Firefox < 10.0.8 or < 16.0, Thunderbird < 10.0.8 or < 16.0, or SeaMonkey < 2.13.

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 10.0.8 / 16.0 or later
Fixed in 10.0.816.0
Interim mitigation

Upgrade affected Mozilla products to Firefox 16.0+/ESR 10.0.8+, Thunderbird 16.0+/ESR 10.0.8+, or SeaMonkey 2.13+ to patch the vulnerability.

Recommended fix High confidence

Firefox 16.0 / Firefox ESR 10.0.8; Thunderbird 16.0 / Thunderbird ESR 10.0.8; SeaMonkey 2.13

  1. Upgrade Firefox to version 16.0 or later (or ESR 10.0.8 for extended support)
  2. Upgrade Thunderbird to version 16.0 or later (or ESR 10.0.8 for extended support)
  3. Upgrade SeaMonkey to version 2.13 or later
  4. Apply updates through your system's package manager (e.g., apt-get update && apt-get upgrade for Ubuntu/Debian, or yum update for RHEL/CentOS)
  5. Restart the affected applications after applying updates
Caveat Major version upgrades (e.g., Firefox 10.x to 16.0) may introduce minor UI changes or compatibility issues with older extensions/plugins; test critical workflows before deploying widely

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
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.

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-2012-4187 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