What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-07 · updated 2026-07-24
• Weakness: CWE-841

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.

Affected products

• randombit botan: from 3.0.0 through 3.11.0

References

• https://github.com/randombit/botan/security/advisories/GHSA-pxcj-9ppx-g86g
• https://access.redhat.com/security/cve/CVE-2026-34582
• https://bugzilla.redhat.com/show_bug.cgi?id=2456285
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34582.json

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