randombit botan up to 3.11.0 Path Validation certificate_known certificate validation

Summaryinfo

A vulnerability was found in randombit botan up to 3.11.0. It has been rated as critical. This affects the function Certificate_Store::certificate_known of the component Path Validation Handler. This manipulation causes certificate validation. This vulnerability is tracked as CVE-2026-34580. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in randombit botan up to 3.11.0. It has been declared as problematic. Affected by this vulnerability is the function Certificate_Store::certificate_known of the component Path Validation Handler. The manipulation with an unknown input leads to a certificate validation vulnerability. The CWE definition for the vulnerability is CWE-295. The product does not validate, or incorrectly validates, a certificate. As an impact it is known to affect integrity. The summary by CVE is:

Botan 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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-34580 since 03/30/2026. The exploitation appears to be difficult. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1587.003 for this issue.

Upgrading to version 3.11.1 eliminates this vulnerability.

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Productinfo

Vendor

• randombit

Name

• botan

Version

• 3.0
• 3.1
• 3.2
• 3.3
• 3.4
• 3.5
• 3.6
• 3.7
• 3.8
• 3.9
• 3.10
• 3.11.0

License

• open-source

Website

• Product: https://github.com/randombit/botan/

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