CVE-2021-21375: Crash in receiving updated SDP answer after initial SDP negotiation failed

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.1% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-03-10 · updated 2026-06-17
Weakness: CWE-400

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.

Affected products

Debian Linux: 9.0
teluu pjsip: through 2.10

References

https://github.com/pjsip/pjproject/commit/97b3d7addbaa720b7ddb0af9bf6f3e443e664365
https://github.com/pjsip/pjproject/security/advisories/GHSA-hvq6-f89p-frvp
https://lists.debian.org/debian-lts-announce/2021/04/msg00023.html
https://lists.debian.org/debian-lts-announce/2021/05/msg00020.html
https://security.gentoo.org/glsa/202107-42
https://github.com/pjsip/pjproject/commit/97b3d7addbaa720b7ddb0af9bf6f3e443e664365
https://github.com/pjsip/pjproject/security/advisories/GHSA-hvq6-f89p-frvp
https://lists.debian.org/debian-lts-announce/2021/04/msg00023.html
https://lists.debian.org/debian-lts-announce/2021/05/msg00020.html
https://security.gentoo.org/glsa/202107-42

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