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Fencer Vulns
medium 5.7

CVE-2024-42491 json

A malformed Contact or Record-Route URI in an incoming SIP request can cause Asterisk to crash when res_resolver_unbound is used

published 2024-09-05 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-39644

cvss
5.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

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.

Patch / fix

  • asterisk asterisk 18.24.3, 20.9.3, 21.4.3
  • asterisk open_source 18.24.3, 20.9.3, 21.4.3
  • digium asterisk 18.24.3, 20.9.3, 21.4.3
  • sangoma asterisk 18.24.3, 20.9.3, 21.4.3
  • asterisk certified_asterisk 18.9-cert12, 20.7-cert2
  • digium certified_asterisk 18.9-cert12, 20.7-cert2
  • sangoma certified_asterisk 18.9-cert12, 20.7-cert2
  • asterisk Debian 14 1:20.9.3~dfsg+~cs6.14.60671435-1

debian advisories DEBIAN-CVE-2024-42491

  • asterisk Alpine 3.18, Alpine 3.17 18.24.3-r0
  • asterisk Alpine 3.24, Alpine 3.23, Alpine 3.22 +3 more 20.9.3-r0

alpine advisories ALPINE-CVE-2024-42491

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-42491 updated cvss 5.7

asterisk: A malformed Contact or Record-Route URI in an incoming SIP request can cause crash

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.58% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H

Affected products

  • asterisk asterisk

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.