CVE-2023-49786: Digium Asterisk

Medium severity, CVSS 5.9. EPSS: 5.3% chance of exploitation in the next 30 days.

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.

Affected products

• Digium Asterisk: before 18.20.1 (fixed in 18.20.1); from 19.0.0, before 20.5.1 (fixed in 20.5.1); version 21.0.0 only
• Sangoma Certified Asterisk: version 13.13.0 only; version 16.8.0 only; version 18.9 only

Published 2023-12-14. Last modified 2026-06-17.