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

> A crafted RealMedia file can cause a crash, hang, or limited memory disclosure in GStreamer's RealMedia demuxer due to missing bounds checks.

- **Severity:** High 7.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 15 Jun 2026
- **Updated:** 8 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-53704, GHSA-j3jj-fwr8-4v9m, UBUNTU-CVE-2026-53704

## What is CVE-2026-53704?

CVE-2026-53704 is a high-severity memory corruption vulnerability in Red Hat Enterprise Linux 10, published on 15 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-53704?


## How do I fix CVE-2026-53704?

Apply the vendor's patch.

## Is CVE-2026-53704 being exploited?

There is no known exploitation of CVE-2026-53704 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53704 and fix it if it is affected.

What it is: CVE-2026-53704 is a high-severity memory corruption vulnerability in Red Hat Enterprise Linux 10, published on 15 Jun 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-53704 in the wild and no public exploit code.

Affected product: Red Hat Enterprise Linux 10. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-53704/ (Markdown: https://insights.sbomify.com/CVE-2026-53704/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53704
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53704
- OSV: https://osv.dev/vulnerability/CVE-2026-53704

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-53704/
Summaries are generated and may contain mistakes; the official description above is the record.