CVE-2024-42491 - CVE House
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Status published Medium CVE-2024-42491

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

Vulnerability 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.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

No credits recorded in the NVD database.

References

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Affected Vendor

Affected Software

asterisk
Vulnerable Versions:
< 18.24.3, >= 19.0.0, < 20.9.3, >= 21.0.0, < 21.4.3, < 18.9-cert12, >= 19.0, < 20.7-cert2

Timeline

Official Publish: September 5th, 2024
Last Modified: November 3rd, 2025
Added to House: July 22nd, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H

Weaknesses (CWE)

CWE-252 CWE-476

MITRE ATT&CK TTPs

T1499 Endpoint Denial of Service
Impact
T1499.004 Application or System Exploitation
Impact
T1489 Service Stop
Impact
T1203 Exploitation for Client Execution
Execution
T1190 Exploit Public-Facing Application
Initial Access