CVE-2009-4629
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 Necko, as used in Thunderbird 3.0.1, SeaMonkey, and other applications, performs DNS prefetching even when the app type is APP_TYPE_MAIL or APP_TYPE_EDITOR, which makes it easier for remote attackers to determine the network location of the application's user by logging DNS requests, as demonstrated by DNS requests triggered by reading text/plain e-mail messages in Thunderbird.
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 Necko networking library performs DNS prefetching even when the application type is set to APP_TYPE_MAIL or APP_TYPE_EDITOR, causing DNS resolution requests to be made when users read text/plain e-mail messages in Thunderbird. This allows remote attackers to determine the user's network location by logging these DNS requests.
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 dataall versions= 3.0.1CVSS 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
- None
- Availability
- None
AV:N/AC:L/Au:N/C:P/I:N/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 the installed Thunderbird versionIn Thunderbird, go to Help > About Thunderbird (or on Windows: Help > About Mozilla Thunderbird) to see the version numberAffected if The version is exactly 3.0.1
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Identify the installed Seamonkey versionIn Seamonkey, go to Help > About Seamonkey to see the version numberAffected if Any version of Seamonkey is installed (all versions are affected)
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Check if DNS prefetching is enabled in ThunderbirdIn Thunderbird, type 'about:config' in the address bar, then search for 'network.dns.disablePrefetch' - verify whether the value is set to false (enabled) or true (disabled)Affected if The preference 'network.dns.disablePrefetch' is set to false, meaning DNS prefetching is enabled
The user is affected if they are running Thunderbird 3.0.1 or any version of Seamonkey with DNS prefetching enabled (network.dns.disablePrefetch set to false).
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 dataThe fix requires modifying Mozilla Necko to respect the application type and disable DNS prefetching for mail and editor applications. Users of affected versions should update to patched versions or disable DNS prefetching in client settings if available.
- Consultation2.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-4629 — 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-2009-4629 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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- 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
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