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FirefoxWeb browser · Mozilla

CVE-2005-4134

MEDIUM · 5.0 CVSS v2.0 Published 2005-12-09
Fix available
A fix is available. Upgrade to after 8.0.40 or later.
See remediation →
59/100
Remediation priority · Elevated
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 1.5, Netscape 8.0.4 and 7.2, and K-Meleon before 0.9.12 allows remote attackers to cause a denial of service (CPU consumption and delayed application startup) via a web site with a large title, which is recorded in history.dat but not processed efficiently during startup. NOTE: despite initial reports, the Mozilla vendor does not believe that this issue can be used to trigger a crash or buffer overflow in Firefox. Also, it has been independently reported that Netscape 8.1 does not have this issue.

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

This is a denial of service vulnerability where large title values stored in the browser's history.dat file cause excessive CPU consumption and delayed application startup when the browser loads its history during initialization. The issue stems from inefficient processing of large title strings during startup, creating a resource exhaustion condition that degrades user experience without causing crashes or buffer overflows.

MitigationUpdate affected browsers to fixed versions (Firefox beyond 1.5, Netscape 8.1+, K-Meleon 0.9.12+) or clear/edit the history.dat file as a workaround. This is a straightforward version update remediation.

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:<= 1.5
K MeleonApplication
Affected:<= 0.9= 0.7= 0.7_service_pack_1= 0.8= 0.8.1= 0.8.2
Mozilla SuiteApplication
Affected:<= 1.7.12
NavigatorApplication
Affected:<= 8.0.40= 7.1= 7.2

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
None
Integrity
None
Availability
Partial

AV:N/AC:L/Au:N/C:N/I:N/A:P

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 browser and version
    Check the browser's About/Help section or use command line: 'firefox --version' for Firefox, or check the executable properties. For Netscape, check Help > About. For K-Meleon, check Help > About.
    Affected if Version is Firefox <=1.5, K-Meleon 0.7-0.9.x, Mozilla Suite <=1.7.12, or Netscape Navigator <=8.0.40/7.1/7.2
  2. Locate the history.dat file
    Search for history.dat in the browser's profile directory. For Firefox/Mozilla Suite, typically in the 'profiles' folder under the user profile path. For Netscape, check the program directory. For K-Meleon, check the application data folder.
    Affected if history.dat file exists in the browser's data directory
  3. Inspect history.dat for large title entries
    Open history.dat with a text editor (it may be in binary or text format). Look for entries with unusually long URL titles, particularly entries with titles exceeding several hundred characters.
    Affected if history.dat contains entries with title values longer than approximately 500+ characters
  4. Verify CPU behavior during startup
    Start the browser while monitoring system CPU usage via Task Manager or system monitor. Observe if there is a noticeable delay (several seconds or more) and high CPU usage during the initial loading phase.
    Affected if Browser exhibits significant startup delay and elevated CPU usage consistent with the described resource exhaustion

A user is affected if their browser version falls within the specified affected range AND their history.dat file contains entries with unusually long title strings, resulting in detectable startup delays or high CPU usage during initialization.

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.

From vendor data
Upgrade available Upgrade to a release after 8.0.40
Interim mitigation

Update affected browsers to fixed versions (Firefox beyond 1.5, Netscape 8.1+, K-Meleon 0.9.12+) or clear/edit the history.dat file as a workaround. This is a straightforward version update remediation.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
4.0 hours of engineering $750
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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-2005-4134 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