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 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.