by Kastro
Paper/Archive/CVE-2026-34582

CVE-2026-34582

randombit botan — Botan has a TLS 1.3 certificate authentication bypass

EPSS 0.2%CVSS 9.1
critical.is priorityof 100
30
CVSS 9.1 (CNA, NVD agree)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 14.3.143 × 202.9No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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

ProductAffectedFixed inSource
botan< 3.11.1–CNA
Red Hat Enterprise Linux 10see advisory–redhat-SADP
Red Hat Enterprise Linux 10see advisory–redhat-SADP

Scores by source

NVD9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
redhat-SADP (CNA)9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
GitHub_M (CNA)8.7CVSS: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 ADPSSVCExploitation: none · Automatable: yes · Technical impact: partial

References

refgithub.com/randombit/botan/security/advisories/GHSA-pxcj-9ppx-g86grefaccess.redhat.com/security/cve/CVE-2026-34582refbugzilla.redhat.com/show_bug.cgi?id=2456285refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34582.json