CVE-2026-34580CWE-295

Botan has a certificate authentication bypass due to trust anchor confusion

Critical · published April 7, 2026

CVSS v4.0
9.3
EPSS
0%
Percentile
23.6
In the wild
Unconfirmed
What it 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 record
Technical detail
CVSS v4.0
9.3 · CRITICAL
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
EPSS
0.00319 · 23.6th percentile
Weakness
CWE-295 · Improper Certificate Validation
Published
2026-04-07T21:12Z
EPSS history
Timeline
  • 07 APR 21:12Z
    Botan has a certificate authentication bypass due to trust anchor confusion
    cvelistv5