CVE-2019-1559

Summary

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).

Impact & exploitability

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products we track (6)

Recommendation

Apply the vendor fix in your normal patch cycle. Open any affected product above for its exact safe version.

Additional information

• NVD record
• http://lists.opensuse.org/opensuse-security-announce/2019-03/msg00041.htmlAdvisory
• http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00019.htmlAdvisory
• http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00046.htmlAdvisory
• http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00047.htmlAdvisory
• http://lists.opensuse.org/opensuse-security-announce/2019-05/msg00049.htmlAdvisory
• http://lists.opensuse.org/opensuse-security-announce/2019-06/msg00080.htmlAdvisory
• http://www.securityfocus.com/bid/107174Advisory
• https://access.redhat.com/errata/RHSA-2019:2304Advisory