OpenSSL 0.9.7 before 0.9.7l, 0.9.8 before 0.9.8d, and earlier versions allows attackers to cause a denial of service (CPU consumption) via parasitic public keys with large (1) "public exponent" or (2) "public modulus" values in X.509 certificates that require extra time to process when using RSA signature verification.
OpenSSL before 0.9.7, 0.9.7 before 0.9.7k, and 0.9.8 before 0.9.8c, when using an RSA key with exponent 3, removes PKCS-1 padding before generating a hash, which allows remote attackers to forge a PKCS #1 v1.5 signature that is signed by that RSA key and prevents OpenSSL from correctly verifying X.509 and other certificates that use PKCS #1.
The default configuration on OpenSSL before 0.9.8 uses MD5 for creating message digests instead of a more cryptographically strong algorithm, which makes it easier for remote attackers to forge certificates with a valid certificate authority signature.
The design of Advanced Encryption Standard (AES), aka Rijndael, allows remote attackers to recover AES keys via timing attacks on S-box lookups, which are difficult to perform in constant time in AES implementations.
ssl3_get_record in s3_pkt.c for OpenSSL before 0.9.7a and 0.9.6 before 0.9.6i does not perform a MAC computation if an incorrect block cipher padding is used, which causes an information leak (timing discrepancy) that may make it easier to launch cryptographic attacks that rely on distinguishing between padding and MAC verification errors, possibly leading to extraction of the original plaintext, aka the "Vaudenay timing attack."
OpenSSL 0.9.6d and earlier, and 0.9.7-beta2 and earlier, does not properly handle ASCII representations of integers on 64 bit platforms, which could allow attackers to cause a denial of service and possibly execute arbitrary code.
Buffer overflows in OpenSSL 0.9.6d and earlier, and 0.9.7-beta2 and earlier, allow remote attackers to execute arbitrary code via (1) a large client master key in SSL2 or (2) a large session ID in SSL3.
The ASN1 library in OpenSSL 0.9.6d and earlier, and 0.9.7-beta2 and earlier, allows remote attackers to cause a denial of service via invalid encodings.
The Pseudo-Random Number Generator (PRNG) in SSLeay and OpenSSL before 0.9.6b allows attackers to use the output of small PRNG requests to determine the internal state information, which could be used by attackers to predict future pseudo-random numbers.