Botan before 3.6.0, when certain GCC versions are used, has a compiler-induced secret-dependent operation in lib/utils/donna128.h in donna128 (used in Chacha-Poly1305 and x25519). An addition can be skipped if a carry is not set. This was observed for GCC 11.3.0 with -O2 on MIPS, and GCC on x86-i386. (Only 32-bit processors can be affected.)

Botan before 3.6.0, when certain LLVM versions are used, has compiler-induced secret-dependent control flow in lib/utils/ghash/ghash.cpp in GHASH in AES-GCM. There is a branch instead of an XOR with carry. This was observed for Clang in LLVM 15 on RISC-V.

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. A bug in the parsing of name constraint extensions in X.509 certificates meant that if the extension included both permitted subtrees and excluded subtrees, only the permitted subtree would be checked. If a certificate included a name which was permitted by the permitted subtree but also excluded by excluded subtree, it would be accepted. Fixed in versions 3.5.0 and 2.19.5.

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.

botan 1.11.x before 1.11.22 improperly handles wildcard matching against hostnames, which might allow remote attackers to have unspecified impact via a valid X.509 certificate, as demonstrated by accepting .example.com as a match for bar.foo.example.com.

botan before 1.11.22 improperly validates certificate paths, which allows remote attackers to cause a denial of service (infinite loop and memory consumption) via a certificate with a loop in the certificate chain.

A padding oracle attack was possible against TLS CBC ciphersuites because if a certain length check on the packet fields failed, a different alert type than one used for message authentication failure would be returned to the sender. This check triggering would leak information about the value of the padding bytes and could be used to perform iterative decryption.

As with most such oracle attacks, the danger depends on the underlying protocol - HTTP servers are particularly vulnerable. The current analysis suggests that to exploit it an attacker would first have to guess several bytes of plaintext, but again this is quite possible in many situations including HTTP.

External references:

http://botan.randombit.net/security.html

Botan before 1.10.13 and 1.11.x before 1.11.22 make it easier for remote attackers to conduct million-message attacks by measuring time differences, related to decoding of PKCS#1 padding.

The BER decoder in Botan 1.10.x before 1.10.10 and 1.11.x before 1.11.19 allows remote attackers to cause a denial of service (memory consumption) via unspecified vectors, related to a length field.

The BER decoder in Botan 0.10.x before 1.10.10 and 1.11.x before 1.11.19 allows remote attackers to cause a denial of service (application crash) via an empty BIT STRING in ASN.1 data.

In Botan 1.11.29 through 1.11.32, RSA decryption with certain padding options had a detectable timing channel which could given sufficient queries be used to recover plaintext, aka an "OAEP side channel" attack.

The Curve25519 code in botan before 1.11.31, on systems without a native 128-bit integer type, might allow attackers to have unspecified impact via vectors related to undefined behavior, as demonstrated on 32-bit ARM systems compiled by Clang.

The X509Certificate::allowedusage function in botan 1.11.x before 1.11.31 might allow attackers to have unspecified impact by leveraging a call with more than one KeyUsage set in the enum value.

Botan before 1.10.13 and 1.11.x before 1.11.29 do not use a constant-time algorithm to perform a modular inverse on the signature nonce k, which might allow remote attackers to obtain ECDSA secret keys via a timing side-channel attack.

Botan 1.11.x before 1.11.29 does not enforce TLS policy for (1) signature algorithms and (2) ECC curves, which allows remote attackers to conduct downgrade attacks via unspecified vectors.

Heap-based buffer overflow in the P-521 reduction function in Botan 1.11.x before 1.11.27 allows remote attackers to cause a denial of service (memory overwrite and crash) or execute arbitrary code via unspecified vectors.

The ressol function in Botan before 1.10.11 and 1.11.x before 1.11.27 allows remote attackers to cause a denial of service (infinite loop) via unspecified input to the OS2ECP function, related to a composite modulus.

Integer overflow in the PointGFp constructor in Botan before 1.10.11 and 1.11.x before 1.11.27 allows remote attackers to overwrite memory and possibly execute arbitrary code via a crafted ECC point, which triggers a heap-based buffer overflow.

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.

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, ecgroup/ecgroup.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.

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.