Asterisk Project Security Advisory – AST-2021-006

Asterisk Project Security Advisory – AST-2021-006

Product Asterisk
Summary Crash when negotiating T.38 with a zero port
Nature of Advisory Remote Crash
Susceptibility Remote Authenticated Sessions
Severity Minor
Exploits Known No
Reported On February 20, 2021
Reported By Gregory Massel
Posted On
Last Updated On February 25, 2021
Advisory Contact bford AT sangoma DOT com
CVE Name CVE-2019-15297

Description When Asterisk sends a re-invite initiating T.38 faxing
and the endpoint responds with a m=image line and zero
port, a crash will occur in Asterisk. This is a
reoccurrence of AST-2019-004.
Modules Affected res_pjsip_t38.c

Resolution If T.38 faxing is not required then setting “t38_udptl” on
the endpoint to “no” disables this functionality. This
option is “no” by default.

If T.38 faxing is required, then Asterisk should be upgraded
to a fixed version.

Affected Versions
Product Release
Series
Asterisk Open Source 16.x 16.16.1
Asterisk Open Source 17.x 17.9.2
Asterisk Open Source 18.x 18.2.1
Certified Asterisk 16.x 16.8-cert6

Corrected In
Product Release
Asterisk Open Source 16.16.2, 17.9.3, 18.2.2
Certified Asterisk 16.8-cert7

Patches
Patch URL Revision
https://downloads.digium.com/pub/security/AST-2021-006-16.diff Asterisk
16
https://downloads.digium.com/pub/security/AST-2021-006-17.diff Asterisk
17
https://downloads.digium.com/pub/security/AST-2021-006-18.diff Asterisk
18
https://downloads.digium.com/pub/security/AST-2021-006-16.8.diff Certified
Asterisk
16.8

Links https://issues.asterisk.org/jira/browse/ASTERISK-29203

https://downloads.asterisk.org/pub/security/AST-2021-006.html

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This document may be superseded by later versions; if so, the latest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
https://downloads.digium.com/pub/security/AST-2021-006.pdf and
https://downloads.digium.com/pub/security/AST-2021-006.html

Revision History
Date Editor Revisions Made
February 25, 2021 Ben Ford Initial revision

Asterisk Project Security Advisory – AST-2021-006
Copyright © 02/25/2021 Digium, Inc. All Rights Reserved.
Permission is hereby granted to distribute and publish this advisory in its
original, unaltered form.