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FirefoxWeb browser · Mozilla

CVE-2006-4253

HIGH · 7.6 CVSS v2.0 Published 2006-08-21
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
85/100
Remediation priority · High
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
Concurrency vulnerability in Mozilla Firefox 1.5.0.6 and earlier allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via multiple Javascript timed events that load a deeply nested XML file, followed by redirecting the browser to another page, which leads to a concurrency failure that causes structures to be freed incorrectly, as demonstrated by (1) ffoxdie and (2) ffoxdie3. NOTE: it has been reported that Netscape 8.1 and K-Meleon 1.0.1 are also affected by ffoxdie. Mozilla confirmed to CVE that ffoxdie and ffoxdie3 trigger the same underlying vulnerability. NOTE: it was later reported that Firefox 2.0 RC2 and 1.5.0.7 are also affected.

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

Concurrency vulnerability in Firefox's JavaScript/XML handling where multiple timed events loading deeply nested XML files combined with page redirects causes memory corruption (incorrect structure freeing), leading to crash or potential arbitrary code execution.

MitigationUpgrade affected browsers (Firefox 1.5.0.7+, 2.0+, or later patched versions) to remediate; Netscape 8.1 and K-Meleon 1.0.1 are also affected.

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:= 0.8= 0.9= 0.9.1= 0.9.2= 0.9.3= 0.10= 0.10.1= 1.0= 1.0.1= 1.0.2= 1.0.3= 1.0.4
K MeleonApplication
Affected:= 1.0.1
NavigatorApplication
Affected:= 8.1

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
High
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:H/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 browser and version
    Open the browser, go to Help > About or check the application version via command line (e.g., firefox --version, or for installed packages: dpkg -l firefox, rpm -q firefox, or reg query for Windows)
    Affected if The browser is Firefox, K-Meleon, or Netscape Navigator and the version matches 0.8, 0.9 through 0.9.3, 1.0 through 1.0.4 for Firefox; 1.0.1 for K-Meleon; or 8.1 for Netscape Navigator
  2. Verify JavaScript is enabled
    In browser settings, check Options/Preferences > Content > Enable JavaScript is checked, or inspect the browser configuration files for js.enabled preference set to true
    Affected if JavaScript is enabled (the vulnerability requires JavaScript for timed events and XML processing)
  3. Confirm XML processing capability
    Verify the browser has XML parsing capability by loading an XML test file or checking that nsIDOMParser is available in the browser
    Affected if XML handling features are present and functional in the browser

You are affected if you are running one of the specific Firefox, K-Meleon, or Netscape Navigator versions listed AND JavaScript is enabled in the browser settings.

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

Upgrade affected browsers (Firefox 1.5.0.7+, 2.0+, or later patched versions) to remediate; Netscape 8.1 and K-Meleon 1.0.1 are also affected.

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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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-2006-4253 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