If an application encounters a fatal protocol error and then calls SSL_shutdown() twice (once to send a close_notify, and once to receive one) 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 "non-stitched" 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 (applications should not do this but some do anyway). Fixed in OpenSSL 1.0.2r (Affected 1.0.2-1.0.2q).
1.0.2g-1ubuntu4.151.0.2n-1ubuntu5.31.0.1f-1ubuntu2.27+esm1Exploitability
AV:NAC:HPR:NUI:NScope
S:UImpact
C:HI:NA:NCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N