CVE-2023-37457: Asterisk is an open source private branch exchange and telephony toolkit

This month

HIGH 7.5REMOTEUPGRADEDOWNGRADE

CVE-2023-37457 is a high-severity flaw (CVSS 7.5) 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 and telephony toolkit. In Asterisk versions 18.20.0 and prior, 20.5.0 and prior, and 21.0.0; as well as ceritifed-asterisk 18.9-cert5 and prior, the 'update' functionality of the PJSIP_HEADER dialplan function can exceed the available buffer space for storing the new value of a header. By doing so this can overwrite memory or cause a crash. This is not externally exploitable, unless dialplan is e

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.1% (top 34%)
CISA exploited list	No
Weakness	CWE-120
Published	2023-12-14
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2023-12-14 20:15 UTCPublished CVE record published
2026-06-17 06:08 UTCUpdated Record last modified

digium asterisk UPGRADE

Affected: <= 18.20.0 · >= 19.0.0 and <= 20.5.0 · 21.0.0

Fixed in: newer than 20.5.0

Safe to downgrade to: a release before 19.0.0

1. Check installed version

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

2. UPGRADE to newer than 20.5.0 (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 19.0.0 (Debian / Ubuntu)

apt-cache madison asterisk sudo apt install asterisk=<VERSION_BEFORE_19.0.0> 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_19.0.0> 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 DOWNGRADE

Affected: 13.13.0 · 13.13.0 cert1 · 13.13.0 cert1-rc1 · 13.13.0 cert1-rc2 · 13.13.0 cert1-rc3 · 13.13.0 cert1-rc4 · 13.13.0 cert2 · 13.13.0 cert3

Fixed in: no fixed release known

Safe to downgrade to: a release before 13.13.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 13.13.0 (Debian / Ubuntu)

apt-cache madison certified-asterisk sudo apt install certified-asterisk=<VERSION_BEFORE_13.13.0> sudo apt-mark hold certified-asterisk

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list certified-asterisk sudo dnf downgrade certified-asterisk-<VERSION_BEFORE_13.13.0> sudo dnf versionlock add certified-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.

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-2023-37457?

asterisk: upgrade to newer than 20.5.0; certified asterisk: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-37457 being exploited?

CVE-2023-37457 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-2023-37457 affect?

CVE-2023-37457 affects asterisk, certified asterisk. Severity is high (CVSS 7.5). Asterisk is an open source private branch exchange and telephony toolkit. In Asterisk versions 18.20.0 and prior, 20.5.0 and prior, and 21.0.0; as well as ceritifed-asterisk 18.9-cert5 and prior, the 'update' functionality of the PJSIP_HEAD

How urgent is CVE-2023-37457?

Priority 48/100. High severity; Remotely exploitable, no login, no user action

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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