GStreamer CVE-2026-52721

Exploitation requires that the GStreamer pcapparse element is actively used within a pipeline - a non-default, debugging-specific configuration absent from typical production GStreamer deployments. A local user with privileges sufficient to execute a GStreamer pipeline must be socially engineered into processing a specially crafted PCAP file supplied by the attacker, satisfying the mandatory user interaction requirement (UI:R). The attacker must have a means to place or deliver the malicious PCAP file on the target system (AV:L). High attack complexity (AC:H) further requires precise crafting of malformed PCAP record structures to reach the vulnerable IPv4/TCP header parsing code paths. Systems where GStreamer is installed but the pcapparse plugin is not in active use for PCAP debugging are not realistically exposed.

The CVSS 3.1 score of 5.3 (Medium) with vector AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:H reflects a genuinely constrained threat model. Local access vector, high attack complexity, and mandatory user interaction together substantially reduce exploitability compared to network-facing or zero-interaction vulnerabilities. No EPSS score was included in the available data, preventing probabilistic exploitation comparison. The vulnerability is absent from the CISA KEV catalog, confirming no known active exploitation at time of analysis, and no public proof-of-concept code has been identified. The pcapparse element's confinement to debugging use cases means most production RHEL deployments are functionally unexposed. The dominant real-world risk is availability impact (crash, A:H) from triggering a segmentation fault; secondary confidentiality impact (C:L) from leaked adjacent memory is realistic but narrow. Integrity is unaffected, consistent with a read-only memory flaw. Overall, this is a low-priority finding for environments not actively using GStreamer PCAP debugging pipelines.

A local attacker or remote actor via phishing delivers a specially crafted PCAP file to a developer or network analyst who uses GStreamer-based PCAP debugging tools on a RHEL system. When the victim opens the file in a pipeline using the pcapparse element, the malformed IPv4/TCP header records trigger out-of-bounds reads during parsing, resulting in either a segmentation fault that crashes the pipeline (denial of service) or exposure of adjacent heap or stack memory that may contain sensitive process data. No proof-of-concept code is known at time of analysis, and the high attack complexity metric (AC:H) indicates that crafting a reliably triggering payload requires precise knowledge of the parser's internal buffer layout.