FirefoxWeb browser · Mozilla
CVE-2011-2362
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 · uneditedMozilla Firefox before 3.6.18, Thunderbird before 3.1.11, and SeaMonkey through 2.0.14 do not distinguish between cookies for two domain names that differ only in a trailing dot, which allows remote web servers to bypass the Same Origin Policy via Set-Cookie headers.
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 confidenceMozilla Firefox before 3.6.18, Thunderbird before 3.1.11, and SeaMonkey through 2.0.14 fail to distinguish between cookies for domain names that differ only by a trailing dot (e.g., example.com vs example.com.). This allows malicious web servers to set cookies for the parent domain that can then be accessed by the trailing-dot variant, enabling Same Origin Policy bypass via Set-Cookie headers.
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
<= 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= 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<= 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= 0.8CVSS 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
- Partial
- Availability
- None
AV:N/AC:L/Au:N/C:N/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 checksWork through these to decide whether this CVE applies to you.
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Identify installed Mozilla productCheck the application name in Add/Remove Programs (Windows), system package manager (Linux), or Application folder (Mac). Look for Firefox, Thunderbird, or SeaMonkey.Affected if Any of these three products is installed
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Determine Firefox versionOpen Firefox, click Help > About Firefox. The version number is displayed in the window title or under the Firefox logo.Affected if Version is 3.6.17 or earlier, or one of: 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
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Determine SeaMonkey versionOpen SeaMonkey, click Help > About SeaMonkey. The version number is displayed.Affected if Version is 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, or 1.1.1
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Determine Thunderbird versionOpen Thunderbird, click Help > About Thunderbird. The version number is displayed.Affected if Version is 3.1.10 or earlier, or one of: 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
If any of these Mozilla products are installed and the version matches one listed in the affected ranges, the environment is vulnerable to cookie domain handling bypass via trailing dot confusion.
Generated from the published advisory. Verify against your own configuration.
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 dataUpgrade affected Mozilla products to versions 3.6.18+ (Firefox), 3.1.11+ (Thunderbird), or 2.0.15+ (SeaMonkey). For legacy systems that cannot upgrade, consider using alternative browsers or implementing additional network-level controls to restrict cookie domain handling.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-2362 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2011-2362 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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