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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

MEDIUM
5.7
CVSS Score
Published: September 5, 2024 at 05:17 PM UTC
Updated: June 17, 2026 at 07:49 AM UTC
3 products affected across 2 vendorsAsteriskCertified AsteriskAsterisk

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Severity
MEDIUM5.7
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Asterisk· Sangoma
95%
v < 18.24.320.0.0 ≤ v < 20.9.321.0.0 ≤ v ≤ 21.4.3
Affected range stops below 18.24.3, so it looks safe — our inference, not a vendor statement
Affected range stops below 20.9.3, so it looks safe — our inference, not a vendor statement
Certified Asterisk· Sangoma
95%
v < 18.918.918.9 cert118.9 cert1-rc118.9 cert1018.9 cert1118.9 cert218.9 cert318.9 cert418.9 cert518.9 cert618.9 cert718.9 cert818.9 cert8-rc118.9 cert8-rc218.9 cert920.7 cert120.7 cert1-rc120.7 cert1-rc220.7 cert2
Affected range stops below 18.9, so it looks safe — our inference, not a vendor statement
Asterisk· Asterisk
60%
v < 18.24.3v < 18.9-cert12v < 20.7-cert2v < 20.9.3v < 21.4.3
Affected range stops below 18.24.3, so it looks safe — our inference, not a vendor statement
Affected range stops below 18.9-cert12, so it looks safe — our inference, not a vendor statement
Affected range stops below 20.7-cert2, so it looks safe — our inference, not a vendor statement
Affected range stops below 20.9.3, so it looks safe — our inference, not a vendor statement
Affected range stops below 21.4.3, so it looks safe — our inference, not a vendor statement

References (7)

x_refsource_MISCPatch
Source: [email protected]
https://github.com/asterisk/asterisk/commit/42a2f4ccfa2c7062a15063e765916b3332e34cc4
x_refsource_MISCPatch
Source: [email protected]
https://github.com/asterisk/asterisk/commit/4f01669c7c41c9184f3cce9a3cf1b2ebf6201742
x_refsource_MISCPatch
Source: [email protected]
https://github.com/asterisk/asterisk/commit/50bf8d4d3064930d28ecf1ce3397b14574d514d2
x_refsource_MISCPatch
Source: [email protected]
https://github.com/asterisk/asterisk/commit/7a0090325bfa9d778a39ae5f7d0a98109e4651c8
x_refsource_MISCPatch
Source: [email protected]
https://github.com/asterisk/asterisk/commit/a15050650abf09c10a3c135fab148220cd41d3a0
x_refsource_CONFIRMVendor Advisory
Source: [email protected]
https://github.com/asterisk/asterisk/security/advisories/GHSA-v428-g3cw-7hv9
Source: af854a3a-2127-422b-91ae-364da2661108
https://lists.debian.org/debian-lts-announce/2024/10/msg00016.html

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.7MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-252CWE-476

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