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FirefoxWeb browser · Mozilla

CVE-2011-2378

HIGH · 10.0 CVSS v2.0 Published 2011-08-18
Fix available
A fix is available. Upgrade to after 3.6.19 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
The appendChild function in Mozilla Firefox before 3.6.20, Thunderbird 3.x before 3.1.12, SeaMonkey 2.x, and possibly other products does not properly handle DOM objects, which allows remote attackers to execute arbitrary code via unspecified vectors that lead to dereferencing of a "dangling pointer."

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 dangling pointer vulnerability exists in the appendChild function of Mozilla Firefox (before 3.6.20), Thunderbird (before 3.1.12), and SeaMonkey 2.x. The function fails to properly handle DOM objects, leading to a dangling pointer that can be dereferenced by remote attackers to achieve arbitrary code execution.

MitigationUpgrade affected products to Firefox 3.6.20+, Thunderbird 3.1.12+, or SeaMonkey 2.x with patches applied. This is a critical remote code execution vulnerability requiring immediate patching.

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:<= 3.6.19= 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= 1.5= 1.5.0.1
ThunderbirdApplication
Affected:= 3.0= 3.0.1= 3.0.2= 3.0.3= 3.0.4= 3.0.5= 3.0.6= 3.0.7= 3.0.8= 3.0.9= 3.0.10= 3.0.11
SeamonkeyApplication
Affected:= 2.0= 2.0.1= 2.0.2= 2.0.3= 2.0.4= 2.0.5= 2.0.6= 2.0.7= 2.0.8= 2.0.9= 2.0.10= 2.0.11

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 product
    Check if Firefox, Thunderbird, or SeaMonkey is installed. On Windows, look in Program Files; on Linux, check /usr/lib or use package manager; on macOS, check /Applications.
    Affected if Any of these three products is installed
  2. Determine Firefox version
    In Firefox, go to Help > About Firefox, or run firefox --version from command line, or check the version file in the installation directory.
    Affected if Version is 3.6.19 or lower, or any 1.0.x (1.0 through 1.0.8) or 1.5.x (1.5, 1.5.0.1) version
  3. Determine Thunderbird version
    In Thunderbird, go to Help > About Thunderbird, or run thunderbird --version from command line, or check the version file in the installation directory.
    Affected if Version is any 3.0.x (3.0 through 3.0.11)
  4. Determine SeaMonkey version
    In SeaMonkey, go to Help > About SeaMonkey, or run seamonkey --version from command line, or check the version file in the installation directory.
    Affected if Version is any 2.0.x (2.0 through 2.0.11)

If the installed product is Firefox 3.6.19 or lower, Firefox 1.0.x/1.5.x, Thunderbird 3.0.x, or SeaMonkey 2.0.x through 2.0.11, the environment is affected by this vulnerability.

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 a release after 3.6.19
Interim mitigation

Upgrade affected products to Firefox 3.6.20+, Thunderbird 3.1.12+, or SeaMonkey 2.x with patches applied. This is a critical remote code execution vulnerability requiring immediate patching.

Recommended fix High confidence

Firefox 3.6.20+ (or modern Firefox ESR/current); Thunderbird 3.1.12+ (or modern Thunderbird); SeaMonkey 2.0.4+ (or modern SeaMonkey)

  1. Identify which Mozilla product is affected (Firefox, Thunderbird, or SeaMonkey)
  2. Check the current installed version of the product
  3. For Firefox: upgrade to version 3.6.20 or later (preferably to a modern supported Firefox version)
  4. For Thunderbird: upgrade to version 3.1.12 or later (preferably to a modern supported Thunderbird version)
  5. For SeaMonkey: upgrade to version 2.0.4 or later (preferably to a modern supported SeaMonkey version)
  6. Restart the application and verify the version has been updated
Caveat Legacy Firefox 3.6.x, Thunderbird 3.x, and SeaMonkey 2.0.x are no longer supported; upgrading to modern versions may require migration of settings and add-on compatibility review

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
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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-2011-2378 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