CVE-2015-2928
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 Hidden Service (HS) server implementation in Tor before 0.2.4.27, 0.2.5.x before 0.2.5.12, and 0.2.6.x before 0.2.6.7 allows remote attackers to cause a denial of service (assertion failure and daemon exit) via unspecified vectors.
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 Hidden Service server implementation in Tor before versions 0.2.4.27, 0.2.5.12, and 0.2.6.7 contains a vulnerability that allows remote attackers to trigger an assertion failure, causing the Tor daemon to exit and resulting in denial of service for the hidden service.
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< 0.2.4.27>= 0.2.5.1, < 0.2.5.12>= 0.2.6.1, < 0.2.6.7CVSS 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:3.1/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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Check installed Tor versionRun 'tor --version' or use your package manager to query the tor package version (dpkg -l tor, rpm -q tor, etc.)Affected if Version is less than 0.2.4.27, or between 0.2.5.1 and 0.2.5.11 inclusive, or between 0.2.6.1 and 0.2.6.6 inclusive
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Identify if hidden service is configuredExamine the Tor configuration file (typically /etc/tor/torrc or /usr/local/etc/torrc) for HiddenServiceDir directives, or check for the presence of a hidden_service directory with hostname and private_key files in Tor's data directoryAffected if A hidden service is configured and the Tor version is in the affected ranges from step 1
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Verify Tor daemon is runningCheck if the tor process is active using 'ps aux | grep tor' or by testing connectivity to the configured hidden service portsAffected if The tor daemon is running with hidden service configuration and the version is vulnerable
Your environment is affected if your Tor version falls within the vulnerable ranges AND you have a hidden service configured and running.
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 data0.2.4.270.2.5.120.2.6.7
Upgrade Tor to version 0.2.4.27, 0.2.5.12, 0.2.6.7 or later. Ensure hidden service private keys are backed up before upgrading to maintain service continuity.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-2928 — 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-2015-2928 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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