CVE-2026-34580
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 · uneditedBotan is a C++ cryptography library. In 3.11.0, the function Certificate_Store::certificate_known had a misleading name; it would return true if any certificate in the store had a DN (and subject key identifier, if set) matching that of the argument. It did not check that the cert it found and the cert it was passed were actually the same certificate. In 3.11.0 an extension of path validation logic was made which assumed that certificate_known only returned true if the certificates were in fact identical. The impact is that if an end entity certificate is presented, and its DN (and subject key identifier, if set) match that of any trusted root, the end entity certificate is accepted immediately as if it itself were a trusted root. , This vulnerability is fixed in 3.11.1.
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 confidenceIn Botan 3.11.0, the Certificate_Store::certificate_known function only checked if a certificate's DN (and optional SKI) matched ANY certificate in the store, but did not verify the certificates were identical. The path validation logic assumed this function only returned true for exact certificate matches. An attacker can present an end-entity certificate with the same DN/SKI as a trusted root, causing it to be accepted as a trusted root and bypassing chain validation.
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= 3.11.0CVSS 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
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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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Identify installed Botan versionRun 'botan --version' or check the library version programmatically using Botan's version reporting functionsAffected if The version reported is exactly 3.11.0
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Confirm Botan is being used for certificate validationReview application code or configuration to verify that Botan is being used for TLS certificate validation or certificate path buildingAffected if Botan is used for certificate validation with trusted roots configured
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Inspect certificate store configurationCheck for any certificates configured as trusted roots in the application's certificate storeAffected if The application maintains a certificate store with trusted root certificates
You are affected only if you are running exactly Botan version 3.11.0 and using it for certificate validation with trusted roots in a certificate store.
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.
dbcve · scopedUpgrade Botan library from 3.11.0 to 3.11.1 or later.
Botan 3.11.1
- 1. Identify all systems and applications using Botan library version 3.11.0
- 2. Update Botan to version 3.11.1 or later which contains the fix for the improper certificate validation vulnerability
- 3. Rebuild and recompile any applications that link against the Botan library
- 4. Verify the update was successful by checking the Botan version
- 5. Test that certificate validation is working correctly in affected applications
- 6. Deploy the updated library to all production environments
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2026-34580 — 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-2026-34580 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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