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FirefoxWeb browser · Mozilla

CVE-2011-2371

HIGH · 10.0 CVSS v2.0 Published 2011-06-30
Fix available
A fix is available. Upgrade to after 3.6.17 or later.
See remediation →
100/100
Remediation priority · Urgent
High EPSS 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
Integer overflow in the Array.reduceRight method in Mozilla Firefox before 3.6.18 and 4.x through 4.0.1, Thunderbird before 3.1.11, and SeaMonkey through 2.0.14 allows remote attackers to execute arbitrary code via vectors involving a long JavaScript Array object.

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

Integer overflow vulnerability in Mozilla Firefox, Thunderbird, and SeaMonkey's JavaScript Array.reduceRight() method allows remote attackers to execute arbitrary code by supplying a specially crafted long JavaScript Array object that triggers the overflow during array processing.

MitigationUpdate affected Mozilla products (Firefox to 3.6.18+/4.0.2+, Thunderbird to 3.1.11+, SeaMonkey to 2.0.14+) or later patched versions to remediate this 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:<= 3.6.17= 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
SeamonkeyApplication
Affected:= 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= 1.0.9= 1.1= 1.1.1
ThunderbirdApplication
Affected:<= 3.1.10= 0.1= 0.2= 0.3= 0.4= 0.5= 0.6= 0.7= 0.7.1= 0.7.2= 0.7.3= 0.8

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 for installed Mozilla applications: look for Firefox, Thunderbird, or SeaMonkey in system installed programs, or run commands like 'firefox --version', 'thunderbird --version', or 'seamonkey --version'
    Affected if Any of Firefox, Thunderbird, or SeaMonkey is installed
  2. Determine installed version
    Run the version command for the identified product, or check Help > About in the application menu
    Affected if Version matches or is lower than the affected ranges listed for the product
  3. Verify JavaScript is enabled
    In the application, go to Options/Preferences > Content and confirm 'Enable JavaScript' is checked (enabled by default)
    Affected if JavaScript is enabled - this is the default state and required for the vulnerability to be triggerable
  4. Confirm affected version range
    Compare your installed version against: Firefox <= 3.6.17 or 1.0-1.5.x; SeaMonkey 1.0-1.1.x; Thunderbird <= 3.1.10 or 0.x-0.8
    Affected if Your version falls within any of the listed affected versions

You are affected if you have Firefox, Thunderbird, or SeaMonkey installed with a version matching the affected ranges and JavaScript is enabled (default state), as the integer overflow in Array.reduceRight() can be triggered when processing malicious JavaScript content.

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 3.6.17
Interim mitigation

Update affected Mozilla products (Firefox to 3.6.18+/4.0.2+, Thunderbird to 3.1.11+, SeaMonkey to 2.0.14+) or later patched versions to remediate this vulnerability.

Recommended fix High confidence

Firefox 3.6.18+ / Firefox 4.0.2+ / Thunderbird 3.1.11+ / SeaMonkey 2.0.15+

  1. 1. Identify the currently installed Mozilla product (Firefox, Thunderbird, or SeaMonkey) and its exact version number
  2. 2. For Firefox: If version is 3.6.x and <= 3.6.17, upgrade to Firefox 3.6.18 or later; if version is 4.x and <= 4.0.1, upgrade to Firefox 4.0.2 or later
  3. 3. For Thunderbird: If version is 3.1.x and <= 3.1.10, upgrade to Thunderbird 3.1.11 or later
  4. 4. For SeaMonkey: Upgrade to SeaMonkey 2.0.15 or later (which contains the fix for this vulnerability)
  5. 5. After upgrading, verify the new version is correctly installed and test that JavaScript functionality works properly
Caveat Upgrading from Firefox 3.6 to 4.x involves significant UI and extension compatibility changes; consider upgrading to Firefox ESR 3.6 branch for organizations needing stability

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

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $910
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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-2011-2371 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