CVE-2021-46837

res_pjsip_t38 in Sangoma Asterisk 16.x before 16.16.2, 17.x before 17.9.3,
and 18.x before 18.2.2, and Certified Asterisk before 16.8-cert7, allows an
attacker to trigger a crash by sending an m=image line and zero port in a
response to a T.38 re-invite initiated by Asterisk. This is a re-occurrence
of the CVE-2019-15297 symptoms but not for exactly the same reason. The
crash occurs because there is an append operation relative to the active
topology, but this should instead be a replace operation.

Bugs

• <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1018073&gt;