CVE-2026-34582 HIGH

CVE-2026-34582: Botan has a TLS 1.3 certificate authentication bypass

Vendor Randombit
Product botan
Weakness CWE-841
Published April 7, 2026
Last update June 30, 2026

CVSS base score

8.7/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

What the vulnerability does

01Description

Botan is a C++ cryptography library. Prior to version 3.11.1, the TLS 1.3 implementation allowed ApplicationData records to be processed prior to the Finished message being received. A server which is attempting to enforce client authentication via certificates can by bypassed by a client which entirely omits Certificate, CertificateVerify, and the Finished message and instead sends application data records. This vulnerability is fixed in 3.11.1.

Key dates

02Disclosure timeline

April 7, 2026 CVE published
June 30, 2026 Record updated