Critical severity · published Apr 7, 2026
CVE-2026-34582
Botan has a TLS 1.3 certificate authentication bypass
9.1
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 14% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BO
botan · randombit
< 3.11.1 · source: vendor, NVD
RH
Red Hat Enterprise Linux 10 · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-34582
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-34582
Mitigation
https://github.com/randombit/botan/security/advisories/GHSA-pxcj-9ppx-g86g
access.redhat.com
https://access.redhat.com/security/cve/CVE-2026-34582
bugzilla.redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2456285
security.access.redhat.com
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34582.json
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