AST-2013-004: Remote Crash From Late Arriving SIP ACK With SDP

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Asterisk Project Security Advisory – AST-2013-004

Product Asterisk
Summary Remote Crash From Late Arriving SIP ACK With SDP
Nature of Advisory Remote Crash
Susceptibility Remote Unauthenticated Sessions
Severity Major
Exploits Known None
Reported On February 11, 2013
Reported By Colin Cuthbertson
Posted On August 27, 2013
Last Updated On August 27, 2013
Advisory Contact Joshua Colp
CVE Name Pending

Description A remotely exploitable crash vulnerability exists in the
SIP channel driver if an ACK with SDP is received after the
channel has been terminated. The handling code incorrectly
assumes that the channel will always be present.

Resolution A check has now been added which only parses SDP and applies
it if an Asterisk channel is present.

Note that Walter Doekes, OSSO B.V., is responsible for
diagnosing and providing the fix for this issue.

Affected Versions
Product Release Series
Asterisk Open Source 1.8.x and above
Asterisk Open Source 11.x All versions
Certified Asterisk 1.8.15 All versions
Certified Asterisk 11.2 All versions

Corrected In
Product Release
Asterisk Open Source, 11.5.1
Certified Asterisk 1.8.15-cert3, 11.2-cert2

SVN URL Revision Asterisk
1.8 Asterisk
11 Certified
1.8.15 Certified


Asterisk Project Security Advisories are posted at

This document may be superseded by later versions; if so, the latest
version will be posted at and

Revision History
Date Editor Revisions Made
2013-08-22 Joshua Colp Initial revision.

Asterisk Project Security Advisory – AST-2013-004
Copyright (c) 2013 Digium, Inc. All Rights Reserved.
Permission is hereby granted to distribute and publish this advisory in its
original, unaltered form.