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VulnerabilityPublished Updated

CVE-2024-42491: asterisk · Unchecked Return Value

Affects asteriskSource GCVE Database

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Not known to be exploited · CVSS 5.7 Medium · fixed in 21.4.3 : update asterisk when convenient.

Data as of 30 Oct 2026, 02:22 UTC

CVSS 3.1 base score
5.7Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitHub_M)CVSS 3.15.7
Patch
Available – fixed in 21.4.3, 20.9.3, 20.7-cert2 +2
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 5 Sep 2024

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
asterisk asteriskAffected
  • <18.24.3
  • >=19.0.0 <20.9.3
  • >=21.0.0 <21.4.3
  • <18.9-cert12
  • >=19.0 <20.7-cert2
Fixed in
  • 18.24.3
  • 20.9.3
  • 21.4.3
  • 18.9-cert12
  • 20.7-cert2

AI-suggested

Users should upgrade to Asterisk versions 18.24.3, 20.9.3, 21.4.3, or certified versions 18.9-cert12 and 20.7-cert2 where the issue is fixed. Alternatively, as a workaround, disable the res_resolver_unbound module by adding 'noload = res_resolver_unbound.so' in modules.conf or set 'rewrite_contact = yes' on all PJSIP endpoints. Note that these workarounds may not be appropriate for all configurations, so upgrading is the recommended approach.

Description

CVE-2024-42491 is a vulnerability in Asterisk PBX prior to versions 18.24.3, 20.9.3, 21.4.3, and certain certified versions. When Asterisk sends a SIP request to a URI with a host starting with `.1` or `[.1]` while the res_resolver_unbound module is loaded, it crashes with a segmentation fault. The issue is fixed in the specified versions. Workarounds include disabling the res_resolver_unbound module or setting rewrite_contact to yes on all PJSIP endpoints, though these may not suit all configurations.

References

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