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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

Published: Sep 5, 2024Updated: Nov 3, 2025 Sources: CVE List NVD BDUCWE-252
NVD MITRE
5.7CVSSMEDIUM
EPSS Score
0.5%
Top 58.5%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:NAC:LPR:LUI:RS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-252CWE-476

Affected Products

asterisksangoma
On-prem
Communications
certified asterisksangoma
On-prem
Communications / voip-telephony
РЕД ОСООО «Ред Софт»
On-premOS
Operating Systems / linux-distro
AsteriskDigium, Inc.
On-prem
Communications / voip-telephony
asteriskasterisk
On-premWeb App
Communications / voip-telephony
sangomacommercialCACommunicationsaka freepbx, certified asterisk, asterisk
ооо «ред софт»commercialRUOperating Systemsaka red soft
digium, inc.commercialUSCommunicationsaka digium, digium inc.
asteriskoss-projectCommunicationsaka open source, asterisk appliance developer kit

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Impact
Initial Access
View detailed technique mapping

References

https://github.com/asterisk/asterisk/commit/42a2f4ccfa2c7062a15063e765916b3332e34cc4
github.com
https://github.com/asterisk/asterisk/commit/4f01669c7c41c9184f3cce9a3cf1b2ebf6201742
github.com
https://github.com/asterisk/asterisk/commit/50bf8d4d3064930d28ecf1ce3397b14574d514d2
github.com
and 5 more references View all →

Timeline

Published
Sep 5, 2024
Last Updated
Nov 3, 2025

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