Debian LinuxOperating system · Debian
CVE-2018-0490
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 · uneditedAn issue was discovered in Tor before 0.2.9.15, 0.3.1.x before 0.3.1.10, and 0.3.2.x before 0.3.2.10. The directory-authority protocol-list subprotocol implementation allows remote attackers to cause a denial of service (NULL pointer dereference and directory-authority crash) via a misformatted relay descriptor that is mishandled during voting.
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 confidenceA NULL pointer dereference vulnerability in Tor's directory-authority voting mechanism allows remote attackers to crash authority servers by submitting a specially crafted (misformatted) relay descriptor that is mishandled during the voting process.
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
Debian LinuxOperating system
= 9.0<= 0.2.9.14>= 0.3.1.7, <= 0.3.1.9= 0.3.1.1= 0.3.1.2= 0.3.1.3= 0.3.1.4= 0.3.1.5= 0.3.1.6= 0.3.2.1= 0.3.2.2= 0.3.2.3= 0.3.2.4CVSS 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
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 if Tor is configured as a directory authorityInspect the Tor configuration file (typically /etc/tor/torrc or /usr/local/etc/torrc) and search for lines containing 'DirAuthority' or 'BridgeAuthority' directives. These lines enable the directory authority voting functionality.Affected if Tor configuration contains DirAuthority or BridgeAuthority entries (this makes the server a directory authority)
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Determine installed Tor versionRun 'tor --version' from the command line, or check the installed package version via 'dpkg -l | grep tor' on Debian systems, or 'rpm -q tor' on RPM-based systems.Affected if The installed Tor version is 0.2.9.14 or earlier, OR falls within 0.3.1.1 through 0.3.1.9, OR falls within 0.3.2.1 through 0.3.2.4
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Verify running Tor processCheck if the Tor daemon is currently running using 'ps aux | grep tor' or 'systemctl status tor'. Directory authorities must be actively running to participate in voting.Affected if Tor daemon is running and the server is functioning as a directory authority
A server is affected only if it runs Tor as a directory authority (or bridge authority) AND the Tor version matches one of the vulnerable versions listed (not 0.2.9.15, 0.3.1.10, or 0.3.2.10 and later).
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 installations to version 0.2.9.15, 0.3.1.10, or 0.3.2.10 or later to patch the descriptor parsing vulnerability in the directory-authority subprotocol.
Fix this in Debian Linux
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-0490 — 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-2018-0490 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
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