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

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 update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2024-42491 is rated Low Risk (37.5/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.55%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2024-42491

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-24 0.55% 0.55% +0.01%
2 2026-06-15 0.99% 0.55% -0.44%
3 2026-05-08 — 0.99% —

Full EPSS history (19 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2024-42491

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.7 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.1 3.6 [email protected]

Weakness enumeration for CVE-2024-42491

OS Trackers for CVE-2024-42491

vendor priority summary link
alpine — CVE-2024-42491: 1 source package rows (asterisk); 86 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 7, open 79. https://security.alpinelinux.org/vuln/CVE-2024-42491
debian not yet assigned CVE-2024-42491 not yet assigned priority: Debian including 1 source packages (asterisk), 2 status rows across 2 suites (bullseye, sid): resolved 2. https://security-tracker.debian.org/tracker/CVE-2024-42491
ubuntu medium CVE-2024-42491 medium priority: Ubuntu including 1 source packages (asterisk), 9 status rows across 9 suites (bionic, focal, jammy, noble, oracular, plucky, questing, upstream, xenial): needs-triage 7, ignored 2. https://ubuntu.com/security/CVE-2024-42491

Affected software / configurations for CVE-2024-42491

Vendor Product Version Raw CPE
sangoma asterisk < 18.24.3 cpe:2.3:a:sangoma:asterisk:*:*:*:*:*:*:*:*
sangoma asterisk >= 20.0.0, < 20.9.3 cpe:2.3:a:sangoma:asterisk:*:*:*:*:*:*:*:*
sangoma asterisk >= 21.0.0, <= 21.4.3 cpe:2.3:a:sangoma:asterisk:*:*:*:*:*:*:*:*
sangoma certified_asterisk < 18.9 cpe:2.3:a:sangoma:certified_asterisk:*:*:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:-:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert1:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert1-rc1:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert10:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert11:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert2:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert3:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert4:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert5:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert6:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert7:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert8:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert8-rc1:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert8-rc2:*:*:*:*:*:*
sangoma certified_asterisk 18.9 cpe:2.3:a:sangoma:certified_asterisk:18.9:cert9:*:*:*:*:*:*
sangoma certified_asterisk 20.7 cpe:2.3:a:sangoma:certified_asterisk:20.7:cert1:*:*:*:*:*:*
sangoma certified_asterisk 20.7 cpe:2.3:a:sangoma:certified_asterisk:20.7:cert1-rc1:*:*:*:*:*:*
sangoma certified_asterisk 20.7 cpe:2.3:a:sangoma:certified_asterisk:20.7:cert1-rc2:*:*:*:*:*:*
sangoma certified_asterisk 20.7 cpe:2.3:a:sangoma:certified_asterisk:20.7:cert2:*:*:*:*:*:*

References for CVE-2024-42491

cvelogic Threat Intelligence