CVE-2024-42491 Null dereference in asterisk
A malformed SIP URI causes Asterisk to crash when the res_resolver_unbound module is loaded, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2024-42491?
CVE-2024-42491 is a medium-severity vulnerability in asterisk, published on 5 Sep 2024. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
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.
Which versions are affected by CVE-2024-42491?
It affects 2 products.
Products include Sangoma Asterisk, Sangoma Certified Asterisk.
How do I fix CVE-2024-42491?
Upgrade to a fixed version.
Is CVE-2024-42491 being exploited?
There is no known exploitation of CVE-2024-42491 in the wild and no public exploit code.
Other vulnerabilities in asterisk
- CVE-2024-57520 Path traversal in n/a
- CVE-2025-47779 Using malformed From header can forge identity with ";" or NULL in name portion
- CVE-2025-57767 Asterisk can crash from a specifically malformed Authorization header in an incoming SIP request
- CVE-2022-37325 Memory corruption in n/a
- CVE-2025-1131 Asterisk Unsafe Shell Sourcing in safe_asterisk Leads to Local Privilege Escalation
Sources
Also known as ALPINE-CVE-2024-42491, DEBIAN-CVE-2024-42491, GHSA-v428-g3cw-7hv9, UBUNTU-CVE-2024-42491.