CVE-2013-4351
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 · uneditedGnuPG 1.4.x, 2.0.x, and 2.1.x treats a key flags subpacket with all bits cleared (no usage permitted) as if it has all bits set (all usage permitted), which might allow remote attackers to bypass intended cryptographic protection mechanisms by leveraging the subkey.
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 confidenceGnuPG versions 1.4.x, 2.0.x, and 2.1.x incorrectly interpret key flags subpackets. When a subpacket has all bits cleared (indicating no usage permitted), the software treats it as having all bits set (all usage permitted), allowing attackers to use cryptographic subkeys in ways that were explicitly prohibited by the key holder.
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= 1.4.0= 1.4.2= 1.4.3= 1.4.4= 1.4.5= 1.4.6= 1.4.8= 1.4.10= 1.4.11= 1.4.12= 1.4.13= 2.0CVSS 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
- M
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- None
AV:N/AC:M/Au:N/C:P/I:P/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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Check GnuPG versionRun 'gpg --version' or query your package manager for the installed gnupg package versionAffected if The installed version is 1.4.x (1.4.0 through 1.4.13), 2.0.x, or 2.1.x
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Verify key flags on subkeysUse 'gpg --list-packets <keyfile>' to inspect the key flags subpacket in any subkey. Look for the 'key flags' subpacket and note its hexadecimal valueAffected if A subkey shows key flags subpacket with all bits cleared (typically 00 or 00 00) - the vulnerable software will treat this as all bits set
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Test key import behaviorImport or verify a key that contains subkeys with restrictive key flags (subpackets with no bits set indicating no usage permitted) and attempt to use the subkey for an operation that should be prohibitedAffected if The software allows a prohibited subkey operation that should have been blocked based on the key flags (e.g., signing with a subkey marked as non-signing)
You are affected if you run GnuPG versions 1.4.x through 1.4.13, 2.0.x, or 2.1.x and you process OpenPGP keys that contain subkeys with key flags subpackets set to indicate no usage permitted.
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 dataUpdate GnuPG to a patched version that properly validates key flags subpackets. Verify that subkey configurations align with intended usage restrictions after updating.
- Consultation1.0 h
- Implementation1.0 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 $1,376.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2013-4351 — 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-2013-4351 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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