CVE-2021-26713

Name: CVE-2021-26713
Creator: NVD / NIST
Published: 2021-02-19T20:15:13.193+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.85%

Last modified Jun 17, 2026

CVE-2021-26713 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. A stack-based buffer overflow in res_rtp_asterisk.c in Sangoma Asterisk before 16.16.1, 17.x before 17.9.2, and 18.x before 18.2.1 and Certified Asterisk before 16.8-cert6 allows an authenticated WebRTC client to cause an Asterisk crash by sending multiple hold/unhold requests in quick succession. This is caused by a signedness comparison mismatch.. EPSS estimates a 1.85% chance of exploitation in the next 30 days.

Description

A stack-based buffer overflow in res_rtp_asterisk.c in Sangoma Asterisk before 16.16.1, 17.x before 17.9.2, and 18.x before 18.2.1 and Certified Asterisk before 16.8-cert6 allows an authenticated WebRTC client to cause an Asterisk crash by sending multiple hold/unhold requests in quick succession. This is caused by a signedness comparison mismatch.

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

1.85%

76.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-787

Affected Software

Vendor	Product	Versions
Digium	Asterisk	>= 16.0.0, < 16.16.1
Digium	Asterisk	>= 17.0.0, < 17.9.2
Digium	Asterisk	>= 18.0.0, < 18.2.1
Digium	Certified Asterisk	16.8

References

https://downloads.asterisk.org/pub/security/Vendor Advisory
https://downloads.asterisk.org/pub/security/AST-2021-004.htmlVendor Advisory
https://issues.asterisk.org/jira/browse/ASTERISK-29205Vendor Advisory
https://downloads.asterisk.org/pub/security/Vendor Advisory
https://downloads.asterisk.org/pub/security/AST-2021-004.htmlVendor Advisory
https://issues.asterisk.org/jira/browse/ASTERISK-29205Vendor Advisory

Timeline

Published: Feb 19, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-26713?

How severe is CVE-2021-26713?

CVE-2021-26713 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.85% probability of exploitation in the next 30 days.

How do I fix CVE-2021-26713?

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-2021-26713?

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

Scan your code now

Source: NVD / NIST