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OpenAdvisories
High · 8.7 CVE-2026-34582 EUVD-2026-19948

Botan has a TLS 1.3 certificate authentication bypass

Published Apr 7, 2026 · Updated Jul 15, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
randombit botan < 3.11.1 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 botan3 3.11.0+dfsg-2 —
Debian 13 botan3 3.11.0+dfsg-2 —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 botan3 No fix yet —
Ubuntu 26.04 LTS botan3 No fix yet —
Ubuntu 25.10 botan +1 No fix yet —
Ubuntu 20.04 LTS botan No fix yet —
Ubuntu 18.04 LTS botan No fix yet —
Show 2 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu Pro 24.04 LTS botan No fix yet —
Ubuntu Pro 22.04 LTS botan No fix yet —
ReleasePackageFixed inAdvisory
openSUSE Leap 16.0 Botan 3.7.1-160000.3.1 openSUSE-SU-2026:20528-1
ReleasePackageFixed inAdvisory
Alpine v3.24 botan3 3.11.1-r0 —

Azure Linux

ReleasePackageFixed inAdvisory
Azure Linux 3 botan2 No fix yet —

Advisories 1

References