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redhatcveRedhat.comRH:CVE-2019-1559
HistoryOct 08, 2019 - 5:49 p.m.

CVE-2019-1559

2019-10-0817:49:09
redhat.com
access.redhat.com
25

EPSS

0.01

Percentile

83.8%

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).

Mitigation

As a workaround you can disable SHA384 if applications (compiled with OpenSSL) allow for adjustment of the ciphersuite string configuration.