CVE-2021-37706 HIGH

CVE-2021-37706: Potential integer underflow upon receiving STUN message in PJSIP

Vendor Pjsip
Product pjproject
Weakness CWE-191
Published December 22, 2021
Last update November 4, 2025

CVSS base score

7.3/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality Low
Integrity Low

CVSS vector

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

What the vulnerability does

01Description

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 affected versions if the incoming STUN message contains an ERROR-CODE attribute, the header length is not checked before performing a subtraction operation, potentially resulting in an integer underflow scenario. This issue affects all users that use STUN. A malicious actor located within the victim’s network may forge and send a specially crafted UDP (STUN) message that could remotely execute arbitrary code on the victim’s machine. Users are advised to upgrade as soon as possible. There are no known workarounds.

Key dates

02Disclosure timeline

December 22, 2021 CVE published
November 4, 2025 Record updated