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

What is CVE-2026-34582?

CVE-2026-34582 is a high-severity vulnerability in randombit botan, published on 7 Apr 2026.

Official description

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.

Weakness: CWE-166, CWE-841

Which versions are affected by CVE-2026-34582?

It affects 1 product.

Products include Botan Project Botan.

How do I fix CVE-2026-34582?

Upgrade to a fixed version.

Is CVE-2026-34582 being exploited?

There is no known exploitation of CVE-2026-34582 in the wild and no public exploit code.

Other vulnerabilities in randombit botan

• CVE-2021-24115 Information disclosure in n/a Critical 9.8
• CVE-2018-9127 Security feature bypass in n/a Critical 9.8
• CVE-2015-7826 Security feature bypass in n/a Critical 9.8
• CVE-2016-6878 Other in n/a Critical 9.8
• CVE-2016-9132 Integer overflow in n/a Critical 9.8

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2026-34582, AZL-81942, DEBIAN-CVE-2026-34582, GHSA-pxcj-9ppx-g86g, UBUNTU-CVE-2026-34582, openSUSE-SU-2026:20528-1.