CVE-2019-1559

Public on 2019-04-04
Modified on 2019-11-14
Description
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).
Severity
Medium
CVSS v3 Base Score
5.9
See breakdown

Affected Packages

Platform Package Release Date Advisory
Amazon Linux 2 openssl 2019-11-11 17:41 ALAS2-2019-1362
Amazon Linux 2 openssl 2019-04-04 21:45 ALAS2-2019-1188
Amazon Linux 2 openssl 2019-11-11 17:41 ALAS2-2019-1362
Amazon Linux 2 openssl 2019-04-04 21:45 ALAS2-2019-1188
Amazon Linux 1 openssl 2019-04-04 19:13 ALAS-2019-1188

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD CVSSv2 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N
NVD CVSSv3 5.9 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N