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AsteriskApplication · Sangoma

CVE-2024-42491

MEDIUM · 5.7 CVSS v3.1 Published 2024-09-05
Fix available
A fix is available. Upgrade to 18.9 / 18.24.3 or later.
See remediation →
61/100
Remediation priority · Elevated
Remotely reachable Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
AsteriskApplication
Affected:< 18.24.3>= 20.0.0, < 20.9.3>= 21.0.0, <= 21.4.3
Certified AsteriskApplication
Affected:< 18.9= 18.9= 20.7

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 18.9 / 18.24.3 / 20.9.3 or later
Fixed in 18.918.24.320.9.3
Vendor patch github.com →
Recommended fix High confidence

Asterisk: 18.24.3 (for 18.x branch), 20.9.3 (for 20.x branch), or 21.4.3 (for 21.x branch); Certified Asterisk: 18.9-cert12 or 20.7-cert2

  1. Identify the currently running Asterisk edition (Asterisk or Certified Asterisk) and version using 'core show version'
  2. Determine the major version branch currently in use (18.x, 20.x, or 21.x)
  3. For Asterisk installations: Upgrade to version 18.24.3, 20.9.3, or 21.4.3 depending on your current branch
  4. For Certified Asterisk installations: Upgrade to version 18.9-cert12 or 20.7-cert2 depending on your current branch
  5. After upgrade, verify the new version is running with 'core show version'
  6. Test SIP functionality to ensure the crash no longer occurs
  7. Alternatively, if upgrading is not feasible, apply workaround: Add 'noload = res_resolver_unbound.so' to modules.conf to disable the vulnerable module
  8. Alternatively, apply workaround: Set 'rewrite_contact = yes' on all PJSIP endpoints
Caveat Standard upgrade risks apply; review Asterisk release notes for any configuration or feature changes in the target version

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-42491 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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