CVE-2024-42491: asterisk Null Dereference — Fix

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.

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CVSS v3.1 Score

5.7

MEDIUM

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

Weakness Type (CWE)

CWE-252 CWE-252

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
sangoma	asterisk	< 18.24.3
sangoma	asterisk	20.0.0 — 20.9.3
sangoma	asterisk	21.0.0 — 21.4.3
sangoma	certified_asterisk	< 18.9
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All
sangoma	certified_asterisk	All

References

Advisories & Patches

https://github.com/asterisk/asterisk/commit/42a2f4ccfa2c7062a15063e765916b3332e34cc4 https://github.com/asterisk/asterisk/commit/4f01669c7c41c9184f3cce9a3cf1b2ebf6201742 https://github.com/asterisk/asterisk/commit/50bf8d4d3064930d28ecf1ce3397b14574d514d2 https://github.com/asterisk/asterisk/commit/7a0090325bfa9d778a39ae5f7d0a98109e4651c8 https://github.com/asterisk/asterisk/commit/a15050650abf09c10a3c135fab148220cd41d3a0 https://github.com/asterisk/asterisk/security/advisories/GHSA-v428-g3cw-7hv9

Other References

https://lists.debian.org/debian-lts-announce/2024/10/msg00016.html

Frequently Asked Questions

What is CVE-2024-42491? +

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. It has a CVSS v3.1 base score of 5.7 (MEDIUM).

How severe is CVE-2024-42491? +

CVE-2024-42491 has a CVSS v3.1 score of 5.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2024-42491? +

CVE-2024-42491 affects products from sangoma, specifically: asterisk, certified_asterisk. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2024-42491? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2024-42491