Bug 2456285 (CVE-2026-34582)

Summary: CVE-2026-34582 botan: Botan: Client authentication bypass in TLS 1.3 implementation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in Botan, a C++ cryptography library. The TLS 1.3 implementation in Botan allows application data to be processed before the TLS handshake is fully completed. A remote attacker can exploit this by omitting critical client authentication messages, such as the Certificate, CertificateVerify, and Finished messages, and instead sending application data. This vulnerability enables a client to bypass server-enforced client authentication, potentially leading to unauthorized access.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 2456399, 2456401, 2456397, 2456398, 2456400, 2456402    
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Description OSIDB Bzimport 2026-04-07 22:02:04 UTC 
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.