Ubuntu LinuxOperating system · Canonical
CVE-2018-9234
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 2.2.4 and 2.2.5 does not enforce a configuration in which key certification requires an offline master Certify key, which results in apparently valid certifications that occurred only with access to a signing 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 2.2.4 and 2.2.5 fail to enforce a configuration requiring an offline master Certify key for key certification operations. This allows apparently valid certifications to be made using only an accessible signing subkey, bypassing the intended security model where the master Certify key should be kept offline and used only for key certification.
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
Ubuntu LinuxOperating system
= 14.04= 16.04= 17.10= 18.04= 2.2.4= 2.2.5CVSS 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
- High
- Integrity
- None
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 installed GnuPG versionRun 'gpg --version' and note the version number in the outputAffected if The version shown is 2.2.4 or 2.2.5 exactly
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List secret keys loaded in GPG agentRun 'gpg --list-secret-keys' to see which private keys are currently accessibleAffected if A secret key with capability 'C' (Certify) is present and loaded, or only signing subkeys are available for certification use
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Inspect key capabilitiesRun 'gpg --edit-key <keyid>' then 'list' to see key capabilities, looking for subkeys with 'C' capability being used for certificationAffected if A subkey with Certify capability is being used instead of a dedicated master Certify key for certification operations
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Check for ultimate trust certificationsUse 'gpg --check-trustdb' or inspect certifications made with 'gpg --list-sigs' to identify certifications at trust level 120 (ultimate) that may have been made with a signing subkeyAffected if Certifications exist that were made using only a signing subkey rather than requiring the offline master Certify key
You are affected if GnuPG version 2.2.4 or 2.2.5 is installed AND key certification operations have been performed using a signing subkey rather than a master Certify key kept offline.
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 dataEnsure GnuPG deployments use an offline master Certify key and implement proper key hierarchy with subkeys used only for signing/encryption operations, following the intended security architecture.
Fix this in Ubuntu Linux
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing2.0 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 $3,168.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-9234 — 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-2018-9234 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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