Vulnerability Advisory : Asterisk: NULL Pointer Dereference in HTTP AMI Digest Authentication with LOW Attack Complexity

Asterisk is an open source private branch exchange and telephony toolkit. Prior to Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3, a NULL pointer dereference in the `Asterisk Manager Interface (AMI)` may allow an unauthenticated attacker to crash Asterisk when `Digest Authentication` is used via `HTTP`. The Asterisk `HTTP` web server, AMI, and AMI access via `HTTP` must all be enabled; each is disabled by default. The attacker must be able to connect to the `HTTP` server, which binds only to `127.0.0.1` by default even when enabled. This issue is fixed in Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3.