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Vulnerability · Published Apr 7, 2026 · Assigned by GitHub_M

CVE-2026-34580Botan has a certificate authentication bypass due to trust anchor confusion

Critical 9.1

In plain English

A critical-severity improper certificate validation in botan from randombit. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.1Critical
Exploit odds (30 days)0.5%top 59.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.24botan33.11.1-r0ALPINE-CVE-2026-34580
Ubuntu:25.10botanno fix listedUBUNTU-CVE-2026-34580
Ubuntu:25.10botan3no fix listedUBUNTU-CVE-2026-34580
Ubuntu:26.04:LTSbotan3no fix listedUBUNTU-CVE-2026-34580
Ubuntu:26.10botan3no fix listedUBUNTU-CVE-2026-34580

Affected products (as reported)

VendorProductVersions
randombit botan >= 3.11.0, < 3.11.1

Weakness: CWE-295 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References