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FirefoxWeb browser · Mozilla

CVE-2011-2998

HIGH · 10.0 CVSS v2.0 Published 2011-09-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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
Integer underflow in Mozilla Firefox 3.6.x before 3.6.23 allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via JavaScript code containing a large RegExp expression.

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 underflow vulnerability in Mozilla Firefox 3.6.x versions before 3.6.23 when processing large RegExp expressions in JavaScript. The vulnerability can cause a denial of service through application crash or potentially allow arbitrary code execution due to improper integer handling in the regex processing routine.

MitigationUpdate Mozilla Firefox to version 3.6.23 or later to patch the integer underflow vulnerability in the RegExp handling code.

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= 3.6.2= 3.6.3= 3.6.4= 3.6.6= 3.6.7= 3.6.8= 3.6.9= 3.6.10= 3.6.11= 3.6.12= 3.6.13

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. Check if Firefox is installed
    Run 'firefox --version' or 'firefox -v' from command line, or look in Add/Remove Programs on Windows
    Affected if Firefox is not installed - not affected
  2. Identify installed Firefox version
    Run 'firefox --version' or open Firefox and go to Help > About Firefox
    Affected if Version shows as 3.6.x where x is 0-22 (e.g., 3.6, 3.6.2, 3.6.13, etc.) - potentially affected
  3. Verify JavaScript is enabled
    In Firefox, go to Options > Content and ensure 'Enable JavaScript' is checked, or check about:config for javascript.enabled
    Affected if JavaScript is disabled - the RegExp vulnerability cannot be triggered since the flaw is in JavaScript regex processing

User is affected if Firefox version 3.6.x (specifically 3.6 through 3.6.22) is installed with JavaScript enabled, as the integer underflow occurs when processing large RegExp expressions in JavaScript.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update Mozilla Firefox to version 3.6.23 or later to patch the integer underflow vulnerability in the RegExp handling code.

Recommended fix High confidence

Firefox 3.6.23 or later (or migrate to a modern Firefox ESR/release branch)

  1. 1. Close all Firefox instances
  2. 2. Back up bookmarks and important data from the current Firefox profile
  3. 3. Download Firefox 3.6.23 or a later stable version from the official Mozilla repository or your distribution's package manager
  4. 4. Install the updated Firefox version using your system's package manager (e.g., 'zypper in MozillaFirefox' for OpenSUSE, 'apt-get install firefox' for Debian)
  5. 5. Verify the installed version by checking Help > About Firefox
  6. 6. Confirm the version displays 3.6.23 or higher
Caveat Firefox 3.6 is obsolete; migrating to modern Firefox may require reconfiguration of extensions/add-ons and may have differences in UI and functionality

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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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-2011-2998 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