CVE-2024-42491: Sangoma Asterisk

Medium severity, CVSS 5.7. EPSS: 0.6% chance of exploitation in the next 30 days.

Asterisk is an open-source private branch exchange (PBX). Prior to versions 18.24.3, 20.9.3, and 21.4.3 of Asterisk and versions 18.9-cert12 and 20.7-cert2 of certified-asterisk, if Asterisk attempts to send a SIP request to a URI whose host portion starts with `.1` or `[.1]`, and res_resolver_unbound is loaded, Asterisk will crash with a SEGV. To receive a patch, users should upgrade to one of the following versions: 18.24.3, 20.9.3, 21.4.3, certified-18.9-cert12, certified-20.7-cert2. Two workarounds are available. Disable res_resolver_unbound by setting `noload = res_resolver_unbound.so` in modules.conf, or set `rewrite_contact = yes` on all PJSIP endpoints. NOTE: This may not be appropriate for all Asterisk configurations.

Affected products

• Sangoma Asterisk: before 18.24.3 (fixed in 18.24.3); from 20.0.0, before 20.9.3 (fixed in 20.9.3); from 21.0.0, up to and including 21.4.3
• Sangoma Certified Asterisk: before 18.9 (fixed in 18.9); version 18.9 only; version 20.7 only

Published 2024-09-05. Last modified 2026-06-17.