CVE-2012-4922
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 tor_timegm function in common/util.c in Tor before 0.2.2.39, and 0.2.3.x before 0.2.3.22-rc, does not properly validate time values, which allows remote attackers to cause a denial of service (assertion failure and daemon exit) via a malformed directory object, a different vulnerability than CVE-2012-4419.
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 tor_timegm function in Tor's common/util.c fails to properly validate time values before processing them. When a malformed directory object containing invalid time data is received, the function triggers an assertion failure that causes the Tor daemon to exit, resulting in a denial of service. This is a distinct vulnerability from CVE-2012-4419.
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<= 0.2.2.38= 0.0.2= 0.0.3= 0.0.4= 0.0.5= 0.0.6= 0.0.6.1= 0.0.6.2= 0.0.7= 0.0.7.1= 0.0.7.2= 0.0.7.3CVSS 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
- None
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:N/A:P
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 Tor versionRun 'tor --version' or check the Tor package version installed via your system's package manager (dpkg, rpm, brew, etc.)Affected if Version is <= 0.2.2.38 or falls within 0.0.2 through 0.0.7.3 range
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Check Tor daemon statusRun 'systemctl status tor' or 'service tor status' to see if the Tor process is currently runningAffected if Tor daemon has exited unexpectedly or is not running
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Examine system logs for assertion failuresReview /var/log/syslog, /var/log/tor/log, or journalctl entries for Tor - look for messages containing 'assertion failure', 'tor_timegm', or unexpected daemon exitsAffected if Logs show assertion failures in tor_timegm or common/util.c related to time validation
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Verify network connectivity to directory authoritiesCheck if Tor can connect to directory authorities and download network status documents - use 'torctl status' or check if new consensus documents are being receivedAffected if Tor crashes upon receiving directory objects, preventing normal operation
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Inspect Tor configuration for directory port exposureExamine torrc for 'DirPort' and 'ORPort' settings - review if the relay is accepting directory requestsAffected if Tor is configured as a relay or directory cache, making it potentially exposed to malformed directory objects
You are affected if your Tor version is <= 0.2.2.38 or in the 0.0.2-0.0.7.3 range AND you observe unexpected daemon exits with assertion failures in logs related to time processing.
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 Tor to version 0.2.2.39 or later, or 0.2.3.22-rc or later, which includes proper validation of time values in the tor_timegm function to prevent assertion failures from malformed directory objects.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2012-4922 — 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-2012-4922 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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- Version or environment caveats, and links to real fixes
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