CVE-2021-46837

Name: CVE-2021-46837
Creator: NVD / NIST
Published: 2022-08-30T07:15:07.417+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.75%

Last modified Jun 17, 2026

CVE-2021-46837 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. res_pjsip_t38 in Sangoma Asterisk 16.x before 16.16.2, 17.x before 17.9.3, and 18.x before 18.2.2, and Certified Asterisk before 16.8-cert7, allows an attacker to trigger a crash by sending an m=image line and zero port in a response to a T.38 re-invite initiated by Asterisk. This is a re-occurrence of the CVE-2019-15297 symptoms but not for exactly the same reason. EPSS estimates a 1.75% chance of exploitation in the next 30 days.

Description

res_pjsip_t38 in Sangoma Asterisk 16.x before 16.16.2, 17.x before 17.9.3, and 18.x before 18.2.2, and Certified Asterisk before 16.8-cert7, allows an attacker to trigger a crash by sending an m=image line and zero port in a response to a T.38 re-invite initiated by Asterisk. This is a re-occurrence of the CVE-2019-15297 symptoms but not for exactly the same reason. The crash occurs because there is an append operation relative to the active topology, but this should instead be a replace operation.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

1.75%

75.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-476

Affected Software

Vendor	Product	Versions
Asterisk	Certified Asterisk	16.8.0
Digium	Asterisk	>= 16.0.0, < 16.16.2
Digium	Asterisk	>= 17.0.0, < 17.9.3
Digium	Asterisk	>= 18.0.0, < 18.2.2
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0
Debian	Debian Linux	11.0

References

https://downloads.asterisk.org/pub/security/AST-2021-006.htmlVendor Advisory
https://lists.debian.org/debian-lts-announce/2022/11/msg00021.htmlMailing List, Third Party Advisory
https://www.debian.org/security/2022/dsa-5285Third Party Advisory
https://downloads.asterisk.org/pub/security/AST-2021-006.htmlVendor Advisory
https://lists.debian.org/debian-lts-announce/2022/11/msg00021.htmlMailing List, Third Party Advisory
https://www.debian.org/security/2022/dsa-5285Third Party Advisory

Timeline

Published: Aug 30, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-46837?

How severe is CVE-2021-46837?

CVE-2021-46837 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.75% probability of exploitation in the next 30 days.

How do I fix CVE-2021-46837?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-46837?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST