CVE-2026-34582
Critical
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.
SeverityCritical
CVSS9.1
Exploit probability—
ProductBotan
PublishedApr 7, 2026
First seenApr 7, 2026
Weakness typeCWE-841CWE-841
How to fix
Sources list no fixed version or patch link for this vulnerability.
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| botan_project botan | 3.0.0 ≤ v ≤ 3.11.0 | — |
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