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Vulnerability record · CVE-2021-46837 · published 30 August 2022

CVE-2021-46837: Certified asterisk null pointer dereference vulnerability

Asterisk · Certified Asterisk

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.

6.5 CVSS 3.1 Medium EPSS 4.4% · top 9.0% CWE-476 · NULL pointer dereference
6.5CVSS 3.1 base score
4.4%EPSS exploitation probability, 30 days
NoNot in CISA KEV
3Affected product versions listed by NVD
6References
17 Jun 2026Last modified by NVD

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.

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

Affected products

3 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://downloads.asterisk.org/pub/security/AST-2021-006.html Vendor Advisory
https://lists.debian.org/debian-lts-announce/2022/11/msg00021.html Mailing ListThird Party Advisory
https://www.debian.org/security/2022/dsa-5285 Third Party Advisory
https://downloads.asterisk.org/pub/security/AST-2021-006.html Vendor Advisory
https://lists.debian.org/debian-lts-announce/2022/11/msg00021.html Mailing ListThird Party Advisory
https://www.debian.org/security/2022/dsa-5285 Third Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2021-46837), CISA KEV, FIRST EPSS (scores of 2026-09-30). This page is refreshed as NVD updates the record.