The Asterisk Development Team would like to announce security releases for
Asterisk 13, 16, 17 and 18, and Certified Asterisk 16.8. The available releases
are released as versions 13.38.2, 16.16.1, 17.9.2, 18.2.1 and 16.8-cert6.
These releases are available for immediate download at
The following security vulnerabilities were resolved in these versions:
AST-2021-001: Remote crash in res_pjsip_diversion
If a registered user is tricked into dialing a
AST-2021-002: Remote crash possible when negotiating T.38
AST-2021-003: Remote attacker could prematurely tear down SRTP calls
An unauthenticated remote attacker could replay SRTP packets which could cause
an Asterisk instance configured without strict RTP validation to tear down
AST-2021-004: An unsuspecting user could crash Asterisk with multiple
Due to a signedness comparison mismatch, an authenticated WebRTC client could
cause a stack overflow and Asterisk crash by sending multiple hold/unhold
requests in quick succession.
AST-2021-005: Remote Crash Vulnerability in PJSIP channel driver
Given a scenario where an outgoing call is placed from Asterisk to a remote
SIP server it is possible for a crash to occur.
For a full list of changes in the current releases, please see the ChangeLogs:
The security advisories are available at:
Thank you for your continued support of Asterisk!