FirefoxWeb browser · Mozilla
CVE-2006-0299
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 · uneditedThe E4X implementation in Mozilla Firefox before 1.5.0.1, Thunderbird 1.5 if running Javascript in mail, and SeaMonkey before 1.0 exposes the internal "AnyName" object to external interfaces, which allows multiple cooperating domains to exchange information in violation of the same origin restrictions.
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 confidenceThe E4X (ECMAScript for XML) implementation in Mozilla Firefox before 1.5.0.1, Thunderbird 1.5, and SeaMonkey before 1.0 exposes the internal 'AnyName' object to external JavaScript interfaces. This allows cooperating malicious domains to bypass same-origin restrictions and exchange information between domains, creating a cross-domain data leakage vulnerability.
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
= 1.5= 1.0= 1.5CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify installed Mozilla productCheck the application name: open the browser or mail client and look at the title bar, or check the program files directory for 'Firefox', 'Thunderbird', or 'SeaMonkey'Affected if The product is Firefox, Thunderbird, or SeaMonkey
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Determine exact version numberFor Firefox: go to Help > About Mozilla Firefox. For Thunderbird: go to Help > About Thunderbird. For SeaMonkey: go to Help > About SeaMonkey. Note the full version number shown (for example, 1.5 or 1.5.0)Affected if Version is 1.5 for Firefox or Thunderbird, or 1.0 for SeaMonkey, or any earlier version
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Check if JavaScript is enabledIn Firefox: Tools > Options > Content > check 'Enable JavaScript'. In Thunderbird: Edit > Preferences > Security > uncheck 'Enable JavaScript'. In SeaMonkey: Edit > Preferences > Script & Plugins > check 'Enable JavaScript'Affected if JavaScript is enabled - E4X is a JavaScript extension and requires JavaScript to be active for the vulnerability to be exploitable
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Verify E4X is accessibleType 'new XML()' in the JavaScript console (Ctrl+Shift+K in Firefox/SeaMonkey). If it returns an XML object rather than an error, E4X is availableAffected if E4X functionality is present - the vulnerability exists in the E4X implementation
You are affected if you are running Firefox 1.5, Thunderbird 1.5, or SeaMonkey 1.0 (or earlier) with JavaScript and E4X enabled.
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 installations to Firefox 1.5.0.1, Thunderbird 1.5.0.1, SeaMonkey 1.0 or later versions. For systems where immediate upgrade is not feasible, consider disabling JavaScript in untrusted contexts or implementing network-level restrictions on vulnerable browser versions.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 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 $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2006-0299 — 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-2006-0299 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