EUVD-2026-17212CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
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3Description
Botan is a C++ cryptography library. Prior to version 3.11.0, during processing of an X.509 certificate path using name constraints which restrict the set of allowable DNS names, if no subject alternative name is defined in the end-entity certificate Botan would check that the CN was allowed by the DNS name constraints, even though this check is technically not required by RFC 5280. However this check failed to account for the possibility of a mixed-case CN. Thus a certificate with CN=Sub.EVIL.COM and no subject alternative name would bypasses an excludedSubtrees constraint for evil.com because the comparison is case-sensitive. This issue has been patched in version 3.11.0.
Analysis
Botan cryptography library versions prior to 3.11.0 fail to properly validate X.509 certificate DNS name constraints due to case-sensitive comparison of the Common Name field, allowing attackers to present certificates with mixed-case Common Names that bypass name constraint restrictions and potentially establish unauthorized secure connections to restricted domains.
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