CVE-2026-52718: GStreamer AV1 Parser Denial of Service Vulnerability

Technical summary

The vulnerability resides in gst-plugins-bad's gst_av1_parser_parse_tile_list_obu() function, which incorrectly passes a byte count to a bit-reader API expecting a bit count. This unit mismatch causes parser state desynchronization and triggers an assertion abort. The root cause is a parameter type mismatch (CWE-617: Assertion with Side Effects) that corrupts the parsing state machine, leading to an uncontrolled crash rather than graceful error handling.

Business impact

Organizations relying on GStreamer-based applications for media workflows—including video streaming platforms, broadcast systems, content management platforms, and multimedia processing services—face service disruption risk. Attacker-controlled content (user-uploaded videos, external feeds, or compromised CDN sources) could trigger crashes, leading to application unavailability and degraded user experience. The impact scales with deployment breadth; desktop applications are vulnerable if they process untrusted media.

Affected systems

GStreamer's gst-plugins-bad component is affected. The vulnerability impacts any application built on GStreamer that processes AV1-encoded video, including but not limited to: media players, video editors, transcoding pipelines, and streaming applications. Systems running GStreamer versions prior to the patched release are vulnerable if they expose AV1 parsing to untrusted input. Specific affected version ranges depend on vendor packaging; verify against GStreamer project advisories.

Exploitability

Exploitability is straightforward: an attacker crafts a malformed AV1 file and tricks or socially engineers a user into opening it—no special privileges, authentication, or local access required. The CVSS vector (AV:N/AC:L/PR:N/UI:R) reflects network-accessible attack surface with only user interaction as a prerequisite. However, successful exploitation requires the victim's system to be running a GStreamer-based application that processes the file, making distribution vector and victim population key factors in real-world risk.

Remediation

Patch GStreamer's gst-plugins-bad to a version containing the fix for the tile list OBU parser function. Consult the official GStreamer security advisories and release notes for exact version numbers and availability timelines. Interim mitigations include restricting AV1 codec support if not essential, disabling auto-play features for media from untrusted sources, and educating users to avoid opening suspicious video files from unknown origins.

Patch guidance

Monitor GStreamer's official release channels and security mailing lists for patches addressing this parser bug. Once patched versions are released, prioritize deployment across systems running media applications with AV1 support. Test patches in non-production environments to ensure compatibility with your media pipeline before rolling out to production. Verify that the patched version includes fixes to gst_av1_parser_parse_tile_list_obu() and its bit-reader integration.

Detection guidance

Monitor application logs for AV1 parser assertion failures, segmentation faults, or codec initialization errors when processing media files from external sources. Implement file-based detection by scanning for malformed AV1 tile list OBU structures in media uploads or feeds—though signature-based approaches may be brittle given the byte/bit mismatch exploit. Network-level detection is challenging; focus on behavioral monitoring (unexpected application crashes after media file access) and input validation at the application layer.

Why prioritize this

MEDIUM severity (CVSS 6.5) reflects the denial-of-service nature without confidentiality or integrity impact. However, prioritization should account for: (1) whether your organization runs GStreamer-based services exposed to user-supplied media; (2) the criticality of continuous media processing to your business; (3) ease of exploitation via social engineering. Organizations processing user-uploaded video should treat this as higher priority; those with isolated, controlled media sources can accept moderate remediation timelines.

Risk score, explained

CVSS 6.5 (MEDIUM) combines a network-accessible attack vector (AV:N) and low attack complexity (AC:L) with user interaction requirement (UI:R) and high availability impact (A:H). The score appropriately reflects that while anyone can craft a malicious file and distribute it, successful exploitation depends on user choice to open it. The absence of confidentiality (C:N) and integrity (I:N) impacts prevents a higher score despite the crash outcome.

Frequently asked questions