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FirefoxWeb browser · Mozilla

CVE-2005-4685

MEDIUM · 6.4 CVSS v2.0 Published 2005-12-31
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
73/100
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
Firefox and Mozilla can associate a cookie with multiple domains when the DNS resolver has a non-root domain in its search list, which allows remote attackers to trick a user into accepting a cookie for a hostname formed via search-list expansion of the hostname entered by the user, or steal a cookie for an expanded hostname, as demonstrated by an attacker who operates an ap1.com Internet web site to steal cookies associated with an ap1.com.example.com intranet web site.

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

Firefox and Mozilla browsers incorrectly associate cookies with multiple domains when the DNS resolver uses a search list. When a user enters a hostname that gets expanded by the DNS search list (e.g., 'ap1' becoming 'ap1.com.example.com'), the browser may accept or leak cookies for the expanded hostname, allowing an attacker on a parent domain to steal cookies intended for the intranet site.

MitigationDisable DNS search list expansion in network configurations or ensure browsers only accept cookies for exact hostnames. For legacy systems, upgrade to patched Firefox/Mozilla versions that enforce strict cookie domain matching.

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
MozillaApplication
Affected:= 0.8= 0.9.2= 0.9.2.1= 0.9.3= 0.9.4= 0.9.4.1= 0.9.5= 0.9.6= 0.9.7= 0.9.8= 0.9.9= 0.9.35

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
Partial
Integrity
Partial
Availability
None

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

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 version
    Check the browser's about dialog or Help > About. For Firefox, go to Help > About Mozilla Firefox. For Mozilla, go to Help > About Mozilla Browser. Note the exact version number (e.g., 1.0.3).
    Affected if The version matches any of: Firefox 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; or Mozilla 0.8, 0.9.2, 0.9.2.1, 0.9.3, 0.9.4, 0.9.4.1, 0.9.5, 0.9.6, 0.9.7, 0.9.8, 0.9.9, 0.9.35
  2. Check DNS search list configuration
    On the operating system, examine the network DNS configuration. On Windows, run 'ipconfig /all' and look for 'DNS Suffix Search List'. On Unix/Linux, check /etc/resolv.conf for 'search' directives. Also check any DHCP or network manager settings.
    Affected if A DNS search list is configured (one or more domain suffixes are present) that can expand short hostnames to fully qualified domain names
  3. Verify cookie behavior with expanded hostname
    Open the browser, go to a short hostname on your intranet (e.g., 'ap1'), observe if the browser sets or accepts cookies for the expanded domain (e.g., 'ap1.com.example.com'). Check the browser's cookie manager to see which domain the cookie is associated with.
    Affected if Cookies are stored for the expanded hostname rather than being rejected or limited to the exact hostname entered

You are affected if you use an affected Firefox or Mozilla version AND have DNS search list expansion enabled, and the browser accepts cookies for DNS-expanded hostnames.

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

Disable DNS search list expansion in network configurations or ensure browsers only accept cookies for exact hostnames. For legacy systems, upgrade to patched Firefox/Mozilla versions that enforce strict cookie domain matching.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
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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-2005-4685 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