CVE-2020-35776

Name: CVE-2020-35776
Creator: NVD / NIST
Published: 2021-02-18T20:15:12.447+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 3.91%

Last modified Jun 17, 2026

CVE-2020-35776 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. A buffer overflow in res_pjsip_diversion.c in Sangoma Asterisk versions 13.38.1, 16.15.1, 17.9.1, and 18.1.1 allows remote attacker to crash Asterisk by deliberately misusing SIP 181 responses.. EPSS estimates a 3.91% chance of exploitation in the next 30 days.

Description

A buffer overflow in res_pjsip_diversion.c in Sangoma Asterisk versions 13.38.1, 16.15.1, 17.9.1, and 18.1.1 allows remote attacker to crash Asterisk by deliberately misusing SIP 181 responses.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

3.91%

89.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-120

Affected Software

Vendor	Product	Versions
Digium	Asterisk	>= 13.0.0, <= 13.38.1
Digium	Asterisk	>= 16.0.0, <= 16.15.1
Digium	Asterisk	>= 17.0.0, <= 17.9.1
Digium	Asterisk	>= 18.0, <= 18.1.1

References

http://packetstormsecurity.com/files/161470/Asterisk-Project-Security-Advisory-AST-2021-001.htmlPatch, Third Party Advisory
http://seclists.org/fulldisclosure/2021/Feb/57Mailing List, Third Party Advisory
https://downloads.asterisk.org/pub/security/AST-2021-001.htmlVendor Advisory
https://issues.asterisk.org/Issue Tracking, Vendor Advisory
https://issues.asterisk.org/jira/browse/ASTERISK-29227Exploit, Issue Tracking, Patch, Vendor Advisory
http://packetstormsecurity.com/files/161470/Asterisk-Project-Security-Advisory-AST-2021-001.htmlPatch, Third Party Advisory
http://seclists.org/fulldisclosure/2021/Feb/57Mailing List, Third Party Advisory
https://downloads.asterisk.org/pub/security/AST-2021-001.htmlVendor Advisory
https://issues.asterisk.org/Issue Tracking, Vendor Advisory
https://issues.asterisk.org/jira/browse/ASTERISK-29227Exploit, Issue Tracking, Patch, Vendor Advisory

Timeline

Published: Feb 18, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-35776?

A buffer overflow in res_pjsip_diversion.c in Sangoma Asterisk versions 13.38.1, 16.15.1, 17.9.1, and 18.1.1 allows remote attacker to crash Asterisk by deliberately misusing SIP 181 responses.

How severe is CVE-2020-35776?

CVE-2020-35776 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 3.91% probability of exploitation in the next 30 days.

How do I fix CVE-2020-35776?

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-2020-35776?

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

Scan your code now

Source: NVD / NIST