CVE-2024-42491: Asterisk is an open-source private branch exchange (PBX)

Q: How do I fix CVE-2024-42491?

asterisk: upgrade to 18.24.3, 20.9.3; certified asterisk: upgrade to 18.9. Exact commands for each OS are on this page.

Q: Is CVE-2024-42491 being exploited?

CVE-2024-42491 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2024-42491 affect?

CVE-2024-42491 affects asterisk, certified asterisk. Severity is medium (CVSS 5.7). 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 hos

Q: How urgent is CVE-2024-42491?

Priority 32/100. No elevated risk signals yet.

Routine

MEDIUM 5.7UPGRADEUPGRADE

CVE-2024-42491 is a medium-severity flaw (CVSS 5.7) affecting asterisk, certified asterisk. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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, cer

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.7 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.6% (top 52%)
CISA exploited list	No
Weakness	CWE-252, CWE-476
Published	2024-09-05
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: sangoma

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2024-09-05 18:15 UTCPublished CVE record published
2026-06-17 07:49 UTCUpdated Record last modified

sangoma asterisk UPGRADE

Affected: < 18.24.3 · >= 20.0.0 and < 20.9.3 · >= 21.0.0 and <= 21.4.3

Fixed in: 18.24.3, 20.9.3

Safe to downgrade to: a release before 20.0.0

1. Check installed version

apt-cache policy asterisk || rpm -q asterisk || asterisk --version

2. UPGRADE to 18.24.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade asterisk

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade asterisk

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 20.0.0 (Debian / Ubuntu)

apt-cache madison asterisk sudo apt install asterisk=<VERSION_BEFORE_20.0.0> sudo apt-mark hold asterisk

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list asterisk sudo dnf downgrade asterisk-<VERSION_BEFORE_20.0.0> sudo dnf versionlock add asterisk

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

sangoma certified asterisk UPGRADE

Affected: < 18.9 · 18.9 · 18.9 cert1 · 18.9 cert1-rc1 · 18.9 cert10 · 18.9 cert11 · 18.9 cert2 · 18.9 cert3

Fixed in: 18.9

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy certified-asterisk || rpm -q certified-asterisk || certified-asterisk --version

2. UPGRADE to 18.9 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade certified-asterisk

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade certified-asterisk

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2024-42491?

asterisk: upgrade to 18.24.3, 20.9.3; certified asterisk: upgrade to 18.9. Exact commands for each OS are on this page.

Is CVE-2024-42491 being exploited?

CVE-2024-42491 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2024-42491 affect?

CVE-2024-42491 affects asterisk, certified asterisk. Severity is medium (CVSS 5.7). 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 hos

How urgent is CVE-2024-42491?

Priority 32/100. No elevated risk signals yet.

Related CVEs

CVE-2025-1131 HIGH 7.8 UPGRADE DOWNGRADE A local privilege escalation vulnerability exists in the safe_asterisk script included with the Asterisk toolk
CVE-2026-23741 NONE 0.0 UPGRADE UPGRADE Asterisk is an open source private branch exchange and telephony toolkit
CVE-2026-23740 NONE 0.0 DOWNGRADE UPGRADE Asterisk is an open source private branch exchange and telephony toolkit
CVE-2026-23739 LOW 2.0 UPGRADE UPGRADE Asterisk is an open source private branch exchange and telephony toolkit
CVE-2026-23738 LOW 3.5 UPGRADE UPGRADE Asterisk is an open source private branch exchange and telephony toolkit

References

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