Botan is a C++ cryptography library. X.509 certificates can identify elliptic curves using either an object identifier or using explicit encoding of the parameters. Prior to 3.5.0 and 2.19.5, checking name constraints in X.509 certificates is quadratic in the number of names and name constraints. An attacker who presented a certificate chain which contained a very large number of names in the SubjectAlternativeName, signed by a CA certificate which contained a large number of name constraints, could cause a denial of service. The problem has been addressed in Botan 3.5.0 and a partial backport has also been applied and is included in Botan 2.19.5.
https://github.com/randombit/botan/security/advisories/GHSA-5gg9-hqpr-r58j
https://github.com/randombit/botan/pull/4187
https://github.com/randombit/botan/pull/4186
https://github.com/randombit/botan/pull/4052
https://github.com/randombit/botan/pull/4047
https://github.com/randombit/botan/pull/4045
https://github.com/randombit/botan/pull/4034
https://github.com/randombit/botan/commit/ff704b12e6fa351aaedd07bffdc91722e84586b8
https://github.com/randombit/botan/commit/c3264821b9f6286ee4e6e3e06826f6b7177e6d41
https://github.com/randombit/botan/commit/7606d70d3a2ac7114476ec2651ca0243c4536fdf
https://github.com/randombit/botan/commit/477822a2d10f02d8ba46c9d8a5132f25843f5cc1
https://github.com/randombit/botan/commit/39535f13c322f56aa3da2f44b2b6abb8619a82ac
https://github.com/randombit/botan/commit/21dccc8fef18c165ba3301d850ac61521f85637e