CVE-2023-49786

Name: CVE-2023-49786
Creator: NVD / NIST
Published: 2023-12-14T20:15:52.927+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.9/10EPSS 5.34%

Last modified Jun 17, 2026

CVE-2023-49786 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. Asterisk is an open source private branch exchange and telephony toolkit. In Asterisk prior to versions 18.20.1, 20.5.1, and 21.0.1; as well as certified-asterisk prior to 18.9-cert6; Asterisk is susceptible to a DoS due to a race condition in the hello handshake phase of the DTLS protocol when handling DTLS-SRTP for media setup. EPSS estimates a 5.34% chance of exploitation in the next 30 days.

Description

Asterisk is an open source private branch exchange and telephony toolkit. In Asterisk prior to versions 18.20.1, 20.5.1, and 21.0.1; as well as certified-asterisk prior to 18.9-cert6; Asterisk is susceptible to a DoS due to a race condition in the hello handshake phase of the DTLS protocol when handling DTLS-SRTP for media setup. This attack can be done continuously, thus denying new DTLS-SRTP encrypted calls during the attack. Abuse of this vulnerability may lead to a massive Denial of Service on vulnerable Asterisk servers for calls that rely on DTLS-SRTP. Commit d7d7764cb07c8a1872804321302ef93bf62cba05 contains a fix, which is part of versions 18.20.1, 20.5.1, 21.0.1, amd 18.9-cert6.

Metrics

CVSS 3.1

5.9/10

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

EPSS Probability

5.34%

91.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions	Update
Digium	Asterisk	< 18.20.1	—
Digium	Asterisk	>= 19.0.0, < 20.5.1	—
Digium	Asterisk	21.0.0	—
Sangoma	Certified Asterisk	13.13.0	—
Sangoma	Certified Asterisk	16.8.0	—
Sangoma	Certified Asterisk	18.9	Cert1

References

http://packetstormsecurity.com/files/176251/Asterisk-20.1.0-Denial-Of-Service.htmlExploit, Third Party Advisory, VDB Entry
http://seclists.org/fulldisclosure/2023/Dec/24Exploit, Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/12/15/7Exploit, Mailing List
https://github.com/EnableSecurity/advisories/tree/master/ES2023-01-asterisk-dtls-hello-raceExploit
https://github.com/asterisk/asterisk/commit/d7d7764cb07c8a1872804321302ef93bf62cba05Patch
https://github.com/asterisk/asterisk/security/advisories/GHSA-hxj9-xwr8-w8pqExploit, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2023/12/msg00019.html
http://packetstormsecurity.com/files/176251/Asterisk-20.1.0-Denial-Of-Service.htmlExploit, Third Party Advisory, VDB Entry
http://seclists.org/fulldisclosure/2023/Dec/24Exploit, Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2023/12/15/7Exploit, Mailing List
https://github.com/EnableSecurity/advisories/tree/master/ES2023-01-asterisk-dtls-hello-raceExploit
https://github.com/asterisk/asterisk/commit/d7d7764cb07c8a1872804321302ef93bf62cba05Patch
https://github.com/asterisk/asterisk/security/advisories/GHSA-hxj9-xwr8-w8pqExploit, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2023/12/msg00019.html

Timeline

Published: Dec 14, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-49786?

How severe is CVE-2023-49786?

CVE-2023-49786 has a CVSS score of 5.9/10 (MEDIUM severity). The EPSS model estimates a 5.34% probability of exploitation in the next 30 days.

How do I fix CVE-2023-49786?

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-2023-49786?

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

Scan your code now

Source: NVD / NIST