CVE-2009-0939
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 · uneditedTor before 0.2.0.34 treats incomplete IPv4 addresses as valid, which has unknown impact and attack vectors related to "Spec conformance," as demonstrated using 192.168.0.
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 · moderate confidenceTor before version 0.2.0.34 incorrectly validates incomplete IPv4 addresses, treating truncated addresses like '192.168.0.' as valid when they should be rejected per specification. This spec conformance issue in the address validation logic could allow malformed IP addresses to be processed.
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<= 0.2.0.33= 0.2.0.1= 0.2.0.2= 0.2.0.3= 0.2.0.4= 0.2.0.5= 0.2.0.6= 0.2.0.10= 0.2.0.11= 0.2.0.12= 0.2.0.13= 0.2.0.14CVSS 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
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:N/AC:L/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 checksWork through these to decide whether this CVE applies to you.
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Check Tor versionRun 'tor --version' or check the package manager (dpkg -l tor, rpm -qa tor)Affected if Version is 0.2.0.33 or lower, or matches one of the specific affected versions: 0.2.0.1 through 0.2.0.6, or 0.2.0.10 through 0.2.0.14
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Identify address validation usageThe vulnerability affects Tor's address parsing which is used whenever Tor processes network addresses for relays, exits, or directory connectionsAffected if Tor is running and processing network addresses (standard operation for any Tor instance)
If your installed Tor version is 0.2.0.33 or lower, or matches any of the specifically listed affected versions (0.2.0.1-0.2.0.6, 0.2.0.10-0.2.0.14), the flawed IP address validation is present in your environment.
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.
dbcve · scopedUpgrade Tor to version 0.2.0.34 or later to obtain the corrected IP address validation logic.
Tor 0.2.0.34
- 1. Backup current Tor configuration and data directory
- 2. Stop the Tor service
- 3. Obtain Tor version 0.2.0.34 or later from the official Tor project (https://www.torproject.org/)
- 4. Install the new version using your system's package manager or by compiling from source
- 5. Restore the backed-up Tor configuration
- 6. Start the Tor service
- 7. Verify the installed version is 0.2.0.34 or later
Generated from the published advisory — verify against the referenced sources before acting.
- 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-2009-0939 — 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-2009-0939 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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