CVE-2021-21375

Name: CVE-2021-21375
Creator: NVD / NIST
Published: 2021-03-10T23:15:12.52+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 2.09%

Last modified Jun 17, 2026

CVE-2021-21375 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. PJSIP is a free and open source multimedia communication library written in C language implementing standard based protocols such as SIP, SDP, RTP, STUN, TURN, and ICE. In PJSIP version 2.10 and earlier, after an initial INVITE has been sent, when two 183 responses are received, with the first one causing negotiation failure, a crash will occur. EPSS estimates a 2.09% chance of exploitation in the next 30 days.

Description

PJSIP is a free and open source multimedia communication library written in C language implementing standard based protocols such as SIP, SDP, RTP, STUN, TURN, and ICE. In PJSIP version 2.10 and earlier, after an initial INVITE has been sent, when two 183 responses are received, with the first one causing negotiation failure, a crash will occur. This results in a denial of service.

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

2.09%

79.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Teluu	Pjsip	<= 2.10
Debian	Debian Linux	9.0

References

https://github.com/pjsip/pjproject/commit/97b3d7addbaa720b7ddb0af9bf6f3e443e664365Patch, Third Party Advisory
https://github.com/pjsip/pjproject/security/advisories/GHSA-hvq6-f89p-frvpExploit, Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/04/msg00023.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/05/msg00020.htmlMailing List, Third Party Advisory
https://security.gentoo.org/glsa/202107-42Third Party Advisory
https://github.com/pjsip/pjproject/commit/97b3d7addbaa720b7ddb0af9bf6f3e443e664365Patch, Third Party Advisory
https://github.com/pjsip/pjproject/security/advisories/GHSA-hvq6-f89p-frvpExploit, Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/04/msg00023.htmlMailing List, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/05/msg00020.htmlMailing List, Third Party Advisory
https://security.gentoo.org/glsa/202107-42Third Party Advisory

Timeline

Published: Mar 10, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-21375?

How severe is CVE-2021-21375?

CVE-2021-21375 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 2.09% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21375?

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-2021-21375?

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

Scan your code now

Source: NVD / NIST