OpenSSL Security Advisory

Scott Neugroschl scott_n at
Wed Feb 27 18:43:59 UTC 2019

Is this a client-side or server-side vulnerability?  Or does it matter?



Scott Neugroschl | XYPRO Technology Corporation
4100 Guardian Street | Suite 100 |Simi Valley, CA 93063 | Phone 805 583-2874|Fax 805 583-0124 |

-----Original Message-----
From: openssl-users <openssl-users-bounces at> On Behalf Of OpenSSL
Sent: Tuesday, February 26, 2019 6:59 AM
To: openssl-project at; OpenSSL User Support ML <openssl-users at>; OpenSSL Announce ML <openssl-announce at>
Subject: OpenSSL Security Advisory

Hash: SHA512

OpenSSL Security Advisory [26 February 2019] ============================================

0-byte record padding oracle (CVE-2019-1559) ============================================

Severity: Moderate

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).

This issue does not impact OpenSSL 1.1.1 or 1.1.0.

OpenSSL 1.0.2 users should upgrade to 1.0.2r.

This issue was discovered by Juraj Somorovsky, Robert Merget and Nimrod Aviram, with additional investigation by Steven Collison and Andrew Hourselt. It was reported to OpenSSL on 10th December 2018.


OpenSSL 1.0.2 and 1.1.0 are currently only receiving security updates. Support for 1.0.2 will end on 31st December 2019. Support for 1.1.0 will end on 11th September 2019. Users of these versions should upgrade to OpenSSL 1.1.1.


URL for this Security Advisory:

Note: the online version of the advisory may be updated with additional details over time.

For details of OpenSSL severity classifications please see:


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