CVE-2026-12892

A flaw was found in GStreamer's gst-plugins-bad package. When processing a specially crafted H.264 video file containing malformed MVC or SVC extension slice NAL units, a 1-byte heap out-of-bounds read can occur during parsing. This happens when the parser attempts to check slice boundary information without first verifying that the NAL unit contains enough data beyond the extension header. An attacker could exploit this by tricking a user into opening a malicious H.264 video file, potentially causing the application to crash or leak a single byte of heap memory.

Red Hat product impact analysis pending. Component mapping required to determine which products ship the affected code. The vulnerable code path specifically affects H.264 NAL extension slices (type 20) used in MVC (Multi-view Video Coding) and SVC (Scalable Video Coding) formats, which are less commonly encountered than baseline H.264. The out-of-bounds read is limited to 1 byte and requires local file access with user interaction (opening a crafted video file). Modern Linux distributions include ASLR and stack canaries which provide some defense-in-depth against heap-based vulnerabilities, though these do not prevent the initial out-of-bounds read from occurring.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

No mitigation is currently available that meets Red Hat Product Security's standards for usability, deployment, applicability, or stability.