CVE-2022-24786 in PJSIP
Summary
by MITRE • 04/06/2022
PJSIP is a free and open source multimedia communication library written in C. PJSIP versions 2.12 and prior do not parse incoming RTCP feedback RPSI (Reference Picture Selection Indication) packet, but any app that directly uses pjmedia_rtcp_fb_parse_rpsi() will be affected. A patch is available in the `master` branch of the `pjsip/pjproject` GitHub repository. There are currently no known workarounds.
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Analysis
by VulDB Data Team • 05/05/2026
The vulnerability CVE-2022-24786 affects PJSIP, a widely-used open-source multimedia communication library written in C that implements various real-time communication protocols including SIP and RTP. This library serves as the foundation for numerous VoIP applications, communication platforms, and multimedia systems across enterprise and consumer environments. The issue specifically targets versions 2.12 and earlier, where the library fails to properly parse incoming RTCP feedback packets with the RPSI (Reference Picture Selection Indication) type. RTCP packets are essential components of the RTP protocol suite used for monitoring transmission quality and providing feedback in real-time multimedia communications. The RPSI packet type is particularly significant in video streaming scenarios as it enables reference picture selection indication, which helps receivers identify which reference pictures should be used for decoding subsequent frames in video streams.
The technical flaw manifests in the pjmedia_rtcp_fb_parse_rpsi() function, which is responsible for parsing RPSI feedback packets in the RTCP protocol. When this function encounters malformed or unexpected RPSI packets, it fails to properly validate or handle the incoming data, creating a potential buffer over-read condition. This occurs because the parsing routine does not adequately check packet boundaries or validate the structure of incoming RPSI data before processing. The vulnerability represents a classic parsing error that can lead to memory corruption and potentially arbitrary code execution if an attacker can control the input data. According to CWE classification, this vulnerability aligns with CWE-129, which describes "Improper Validation of Array Index" and CWE-787, "Out-of-bounds Write" as potential underlying causes. The issue is particularly concerning because it affects direct usage of the parsing function, meaning any application that directly calls pjmedia_rtcp_fb_parse_rpsi() is vulnerable regardless of the broader application architecture.
The operational impact of this vulnerability extends beyond simple denial-of-service scenarios to potentially enable more sophisticated attacks. In multimedia communication systems, attackers could craft malicious RPSI packets that cause the target application to crash or behave unpredictably, leading to service disruption in VoIP systems, video conferencing platforms, or other real-time communication services. The vulnerability is especially dangerous in environments where PJSIP is used in mission-critical applications such as emergency services, healthcare communication systems, or enterprise collaboration platforms where uninterrupted service is essential. Attackers could exploit this weakness to perform persistent service degradation attacks, potentially causing cascading failures in communication networks that rely on PJSIP for their multimedia capabilities. The absence of known workarounds means that organizations must either patch their systems immediately or risk exposure to these potential exploitation vectors, making this vulnerability particularly urgent from a security operations perspective.
Organizations using PJSIP should prioritize upgrading to versions 2.13 or later where the vulnerability has been addressed in the master branch of the pjproject repository. The fix implemented in the patched versions includes proper validation of packet structures and bounds checking to prevent the buffer over-read condition that previously occurred during RPSI packet parsing. Security teams should conduct thorough vulnerability assessments to identify all systems and applications that directly utilize the pjmedia_rtcp_fb_parse_rpsi() function, as these represent the most immediate risk. Additionally, network monitoring should be enhanced to detect unusual RTCP traffic patterns that might indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to T1205.001 "Traffic Signaling" and T1071.004 "Application Layer Protocol: DNS" as attackers might use malformed RTCP packets to probe for vulnerable systems, though the primary concern here is the direct execution of code through memory corruption. The vulnerability also aligns with T1499.004 "Endpoint Denial of Service" and T1595.001 "Network Topology Discovery" as exploitation could lead to service disruption and information gathering. System administrators should implement robust patch management procedures to ensure all instances of PJSIP are updated promptly, as the vulnerability affects the core parsing functionality that underpins many multimedia communication services.