Asterisk Project Security Advisory - AST-2019-005 Product Asterisk Summary Remote Crash Vulnerability in audio transcoding Nature of Advisory Denial of Service Susceptibility Remote Unauthenticated Sessions Severity Minor Exploits Known No Reported On August 7, 2019 Reported By Gregory Massel Posted On Last Updated On August 26, 2019 Advisory Contact Jcolp AT sangoma DOT com CVE Name CVE-2019-15639 Description When audio frames are given to the audio transcoding support in Asterisk the number of samples are examined and as part of this a message is output to indicate that no samples are present. A change was done to suppress this message for a particular scenario in which the message was not relevant. This change assumed that information about the origin of a frame will always exist when in reality it may not. This issue presented itself when an RTP packet containing no audio (and thus no samples) was received. In a particular transcoding scenario this audio frame would get turned into a frame with no origin information. If this new frame was then given to the audio transcoding support a crash would occur as no samples and no origin information would be present. The transcoding scenario requires the â??genericplcâ?? option to be set to enabled (the default) and a transcoding path from the source format into signed linear and then from signed linear into another format. Note that there may be other scenarios that have not been found which can cause an audio frame with no origin to be given to the audio transcoding support and thus cause a crash. Modules Affected main/translate.c Resolution The â??genericplcâ?? option can be disabled in codecs.conf to mitigate the described scenario. It is recommended, however, that Asterisk be upgraded to one of the listed versions or the linked patch applied to protect against potential unknown scenarios. Affected Versions Product Release Series Asterisk Open Source 13.x 13.28.0 Asterisk Open Source 16.x 16.5.0 Corrected In Product Release Asterisk Open Source 13.28.1 Asterisk Open Source 16.5.1 Patches SVN URL Revision http://downloads.asterisk.org/pub/security/AST-2019-005-13.diff Asterisk 13 http://downloads.asterisk.org/pub/security/AST-2019-005-16.diff Asterisk 16 Links https://issues.asterisk.org/jira/browse/ASTERISK-28499 Asterisk Project Security Advisories are posted at http://www.asterisk.org/security This document may be superseded by later versions; if so, the latest version will be posted at http://downloads.digium.com/pub/security/AST-2019-005.pdf and http://downloads.digium.com/pub/security/AST-2019-005.html Revision History Date Editor Revisions Made August 26, 2019 Joshua Colp Initial revision Asterisk Project Security Advisory - AST-2019-005 Copyright © 2019 Digium, Inc. All Rights Reserved. Permission is hereby granted to distribute and publish this advisory in its original, unaltered form.