CVE-2023-49786

Asterisk is an open source private branch exchange and telephony toolkit.
In Asterisk prior to versions 18.20.1, 20.5.1, and 21.0.1; as well as
certified-asterisk prior to 18.9-cert6; Asterisk is susceptible to a DoS
due to a race condition in the hello handshake phase of the DTLS protocol
when handling DTLS-SRTP for media setup. This attack can be done
continuously, thus denying new DTLS-SRTP encrypted calls during the attack.
Abuse of this vulnerability may lead to a massive Denial of Service on
vulnerable Asterisk servers for calls that rely on DTLS-SRTP. Commit
d7d7764cb07c8a1872804321302ef93bf62cba05 contains a fix, which is part of
versions 18.20.1, 20.5.1, 21.0.1, amd 18.9-cert6.