CVE-2026-12891: GStreamer gst-plugins-bad out-of-bounds read in H.266 parser

CVE-2026-12891 · Severity: medium · CVSS 4.3 · Published 2026-06-23

GStreamer is a widely used multimedia framework for processing video and audio. A flaw in its H.266 video processing component allows a specially crafted video file to trigger an out-of-bounds memory read. This could allow an attacker to leak small amounts of sensitive information from the application's memory, potentially compromising user privacy or system security.

Technologies: Gstreamer Gst-Plugins-Bad, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9. Vendors: Gstreamer, Red Hat.

Quick answers

Is CVE-2026-12891 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-12891 being exploited in the wild.
How severe is CVE-2026-12891?
Medium severity, with a CVSS score of 4.3, published 23 June 2026.
Which products and versions are affected?
Gstreamer Gst-Plugins-Bad All versions containing H.266 parser; Red Hat Enterprise Linux 10 affected; Red Hat Enterprise Linux 8 affected; Red Hat Enterprise Linux 9 affected.
Is there a fix for CVE-2026-12891?
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-2026-12891 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-12891?
Check whether you run Gstreamer Gst-Plugins-Bad, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8 or one of the others listed 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

An out-of-bounds read vulnerability exists in the GStreamer gst-plugins-bad package within the H.266/VVC VUI parameter parser. The root cause is a missing bounds check in the `gst_h266_parse_vui_parameters()` function in `gsth266parser.c`, where the `aspect_ratio_idc` field is used as an index into the `aspect_ratios[]` array. While the array contains only 17 entries, the 8-bit field allows values up to 255, leading to an 8-byte out-of-bounds read from the .data section. An attacker can exploit this by providing a malformed H.266 video stream, causing the leaked memory contents to be stored in video metadata (pixel-aspect-ratio), which can then be observed by downstream components or applications.

Affected products

  • GStreamer gst-plugins-bad All versions containing H.266 parser
  • Red Hat Red Hat Enterprise Linux 8 affected
  • Red Hat Red Hat Enterprise Linux 9 affected
  • Red Hat Red Hat Enterprise Linux 10 affected

Timeline

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

References

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