Package Instance

Integer Overflow or Wraparound
Calls to `EVP_CipherUpdate`, `EVP_EncryptUpdate` and `EVP_DecryptUpdate` may overflow the output length argument in some cases where the input length is close to the maximum permissable length for an integer on the platform. In such cases the return value from the function call will be 1 (indicating success), but the output length value will be negative. This could cause applications to behave incorrectly or crash.

Integer Overflow or Wraparound
The OpenSSL public API function `X509_issuer_and_serial_hash()` attempts to create a unique hash value based on the issuer and serial number data contained within an X509 certificate. However it fails to correctly handle any errors that may occur while parsing the issuer field (which might occur if the issuer field is maliciously constructed). This may subsequently result in a NULL pointer deref and a crash leading to a potential denial of service attack.

Inadequate Encryption Strength
OpenSSL supports SSLv2. If a client attempts to negotiate SSLv2 with a server that is configured to support both SSLv2 and more recent SSL and TLS versions then a check is made for a version rollback attack when unpadding an RSA signature. Clients that support SSL or TLS versions greater than SSLv2 are supposed to use a special form of padding. A server that supports greater than SSLv2 is supposed to reject connection attempts from a client where this special form of padding is present, because this indicates that a version rollback has occurred (i.e. both client and server support greater than SSLv2, and yet this is the version that is being requested). The implementation of this padding check inverted the logic so that the connection attempt is accepted if the padding is present, and rejected if it is absent. This means that such as server will accept a connection if a version rollback attack has occurred. Further the server will erroneously reject a connection if a normal SSLv2 connection attempt is made. In order to be vulnerable a server must: 1) have configured SSLv2 support at compile time (this is off by default), 2) have configured SSLv2 support at runtime (this is off by default), 3) have configured SSLv2 ciphersuites (these are not in the default ciphersuite list) The underlying error is in the implementation of the `RSA_padding_check_SSLv23()` function. This also affects the `RSA_SSLV23_PADDING` padding mode used by various other functions.