bcrypt password hashing in Botan before 2.1.0 does not correctly handle passwords with a length between 57 and 72 characters, which makes it easier for attackers to determine the cleartext password.

In Botan before 2.19.3, it is possible to forge OCSP responses due to a certificate verification error. This issue was introduced in Botan 1.11.34 (November 2016).

The ElGamal implementation in Botan through 2.18.1, as used in Thunderbird and other products, allows plaintext recovery because, during interaction between two cryptographic libraries, a certain dangerous combination of the prime defined by the receiver's public key, the generator defined by the receiver's public key, and the sender's ephemeral exponents can lead to a cross-configuration attack against OpenPGP.

In Botan before 2.17.3, constant-time computations are not used for certain decoding and encoding operations (base32, base58, base64, and hex).

A side-channel issue was discovered in Botan before 2.9.0. An attacker capable of precisely measuring the time taken for ECC key generation may be able to derive information about the high bits of the secret key, as the function to derive the public point from the secret scalar uses an unblinded Montgomery ladder whose loop iteration count depends on the bitlength of the secret. This issue affects only key generation, not ECDSA signatures or ECDH key agreement.

Botan 2.5.0 through 2.6.0 before 2.7.0 allows a memory-cache side-channel attack on ECDSA signatures, aka the Return Of the Hidden Number Problem or ROHNP, related to dsa/dsa.cpp, ec_group/ec_group.cpp, and ecdsa/ecdsa.cpp. To discover an ECDSA key, the attacker needs access to either the local machine or a different virtual machine on the same physical host.

An issue was discovered in Botan 1.11.32 through 2.x before 2.6.0. An off-by-one error when processing malformed TLS-CBC ciphertext could cause the receiving side to include in the HMAC computation exactly 64K bytes of data following the record buffer, aka an over-read. The MAC comparison will subsequently fail and the connection will be closed. This could be used for denial of service. No information leak occurs.

Botan 2.2.0 - 2.4.0 (fixed in 2.5.0) improperly handled wildcard certificates and could accept certain certificates as valid for hostnames when, under RFC 6125 rules, they should not match. This only affects certificates issued to the same domain as the host, so to impersonate a host one must already have a wildcard certificate matching other hosts in the same domain. For example, b*.example.com would match some hostnames that do not begin with a 'b' character.

A cryptographic cache-based side channel in the RSA implementation in Botan before 1.10.17, and 1.11.x and 2.x before 2.3.0, allows a local attacker to recover information about RSA secret keys, as demonstrated by CacheD. This occurs because an array is indexed with bits derived from a secret key.

A programming error exists in a way Randombit Botan cryptographic library version 2.0.1 implements x500 string comparisons which could lead to certificate verification issues and abuse. A specially crafted X509 certificate would need to be delivered to the client or server application in order to trigger this vulnerability.