# CVE-2026-34582: botan3: Botan is a C++ cryptography library

CVE-2026-34582 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-34582, released April 7, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-34582
- Priority: Urgent
- CVSS: 9.1 (critical)
- EPSS: 0.0024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 7, 2026

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | Botan opensuse-leap 16.0 | 3.7.1-160000.3.1 | [OPENSUSE-SU-2026:20528-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20528-1.md) | Apr 14, 2026 |
| Linux | botan3 Debian 13.5 (trixie) | 3.11.0+dfsg-2 | [DEBIAN-CVE-2026-34582](https://patchblox.com/security/data/fix/linux/debian-cve-2026-34582.md) | Apr 7, 2026 |
| Linux | botan3 Debian 14 | 3.11.0+dfsg-2 | [DEBIAN-CVE-2026-34582](https://patchblox.com/security/data/fix/linux/debian-cve-2026-34582.md) | Apr 7, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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