EUVD-2026-19948
CVSS 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
3Description
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.
Analysis
TLS 1.3 client authentication bypass in Botan cryptography library versions prior to 3.11.1 allows unauthenticated remote attackers to skip certificate validation by sending ApplicationData records before the Finished handshake message. Exploiting this vulnerability requires no authentication (PR:N), low attack complexity (AC:L), and no user interaction (UI:N), resulting in complete integrity compromise (VI:H) for TLS 1.3 servers relying on mutual authentication. …
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Remediation
Within 24 hours: Identify all systems running Botan cryptography library and determine current version (check /usr/lib/libbotan* or equivalent; query application dependencies). Within 7 days: Contact Botan maintainers and your software vendors for patch timeline and interim guidance; prepare patching plan for Botan 3.11.1 or later. …
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External POC / Exploit Code
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