# CVE-2026-12892: GStreamer gst-plugins-bad heap out-of-bounds read in H.264 parser

Source: https://junglewise.ai/threats/cve-2026-12892-gstreamer-gst-plugins-bad-heap-out-of-bounds-read-in-h-264-parser  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-23. Updated: 2026-06-23  
License: CC BY 4.0 with a link back

CVE-2026-12892 · Severity: medium · CVSS 4.4 · Published 2026-06-23

A vulnerability exists in GStreamer, a widely used multimedia framework for processing video and audio. By tricking a user into opening a specially crafted H.264 video file, an attacker can cause the application to crash or potentially leak a small amount of memory. This could lead to service disruptions for applications relying on GStreamer for video playback or processing.

Technologies: [Gstreamer](https://junglewise.ai/threats/technologies/gstreamer). Vendors: [Gstreamer](https://junglewise.ai/threats/vendors/gstreamer).

## Quick answers

**Is CVE-2026-12892 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-12892 being exploited in the wild.

**How severe is CVE-2026-12892?** Medium severity, with a CVSS score of 4.4, published 23 June 2026.

**Which products and versions are affected?** Gstreamer 1.x up to 1.29.1.1.

**Is there a fix for CVE-2026-12892?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-12892 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-12892?** Check whether you run Gstreamer at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A 1-byte heap out-of-bounds read exists in the gst_h264_parse_process_nal() function within gsth264parse.c. The vulnerability occurs when processing H.264 NAL units of type GST_H264_NAL_SLICE_EXT (type 20) used for MVC/SVC extensions. The parser attempts to check the first_mb_in_slice flag by dereferencing data at an offset equal to the header size (4 bytes) without verifying that the NAL unit contains data beyond that header. An attacker can exploit this by providing a malformed NAL unit with a size exactly equal to the header length, causing a read beyond the allocated buffer. This requires a user to open a malicious video file and can result in a Denial of Service (crash) or a single-byte information leak.

## Affected products

- Red Hat gst-plugins-bad-free Enterprise Linux 6, 7, 8, 9, 10
- GStreamer GStreamer 1.x up to 1.29.1.1

## Timeline

- 2026-06-22: disclosed: Reported by CoE-CNDS Lab researchers to Red Hat Bugzilla.
- 2026-06-23: advisory: NVD and Red Hat published advisory details.

## References

- [https://access.redhat.com/downloads/content/package-browser/](https://access.redhat.com/downloads/content/package-browser/)
- [https://access.redhat.com/security/cve/CVE-2026-12892](https://access.redhat.com/security/cve/CVE-2026-12892)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2491321](https://bugzilla.redhat.com/show_bug.cgi?id=2491321)
- [https://gitlab.freedesktop.org/gstreamer/gstreamer/-/work_items/5108](https://gitlab.freedesktop.org/gstreamer/gstreamer/-/work_items/5108)

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