If an application encounters a fatal protocol error and then calls SSL_shutdown twice then OpenSSL can respond differently to the calling application if a 0 byte record is received with invalid padding compared to if a 0 byte record is received with an invalid MAC. If the application then behaves differently based on that in a way that is detectable to the remote peer, then this amounts to a padding oracle that could be used to decrypt data. In order for this to be exploitable quot;non-stitchedquot; ciphersuites must be in use. Stitched ciphersuites are optimised implementations of certain commonly used ciphersuites. Also the application must call SSL_shutdown twice even if a protocol error has occurred . Fixed in OpenSSL 1.0.2r . The OpenSSL DSA signature algorithm has been shown to be vulnerable to a timing side channel attack. An attacker could use variations in the signing algorithm to recover the private key. Fixed in OpenSSL 1.1.1a . Fixed in OpenSSL 1.1.0j . Fixed in OpenSSL 1.0.2q