What is CVE-2024-42491?

CVE-2024-42491 is a medium-severity vulnerability in Asterisk, classified under CWE-252. CVSS score: 5.7/10. Published 2024-09-05.

How severe is CVE-2024-42491?

Medium severity. CVSS v3 base score is 5.7 out of 10.

NULL pointer dereference in Asterisk

CVE-2024-42491

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.

Published 2024-09-05 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.006 (45.6th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 45.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: -0.000

Affected products

Asterisk — versions < 18.24.3, >= 19.0.0, < 20.9.3, >= 21.0.0, < 21.4.3
Sangoma Asterisk
Sangoma Certified Asterisk — versions 18.9, 20.7

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2024-42491?: CVE-2024-42491 is a medium-severity vulnerability in Asterisk, classified under CWE-252. CVSS score: 5.7/10. Published 2024-09-05.
How severe is CVE-2024-42491?: Medium severity. CVSS v3 base score is 5.7 out of 10.