CVE-2026-53703 Gstreamer1-plugins-ugly-free: gstreamer: out-of-bounds read in realmedia demuxer audio stream header parser

High 7.1 Published 15 Jun 2026 Updated 5 Aug 2026

A malicious RealMedia file can trigger an out-of-bounds read in GStreamer, potentially leaking memory data or crashing the application.

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

What is CVE-2026-53703?

CVE-2026-53703 is a high-severity 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 vulnerability was found in the GStreamer RealMedia demuxer (gst-plugins-ugly). When processing a RealMedia (.rm) file, the demuxer parses MDPR (media properties) chunks to configure audio streams. For audio stream header versions 4 and 5, the parser reads fields such as codec type, packet size, sample rate, channel count, and extra codec data length from fixed offsets within the chunk without first checking that the chunk contains enough data. If a malicious file provides an MDPR chunk that is too small to contain a complete audio stream header, the parser reads beyond the end of the buffer. This can cause the application to crash. In some cases, bytes read past the buffer boundary may be incorporated into stream metadata, which could result in limited information disclosure.

Weakness: CWE-125

Which versions are affected by CVE-2026-53703?

Linux distribution packages (2)

`gstreamer1-plugins-ugly-free` AlmaLinux:10	All versions	`1.26.7-2.el10_2.1`
`gstreamer1-plugins-ugly-free` Rocky Linux:10	All versions	`0:1.26.7-2.el10_2.1`

How do I fix CVE-2026-53703?

Apply the vendor's patch.

Is CVE-2026-53703 being exploited?

There is no known exploitation of CVE-2026-53703 in the wild and no public exploit code.

Sources

Also known as ALSA-2026:36673, DEBIAN-CVE-2026-53703, GHSA-hghw-p2mw-fvch, RLSA-2026:36673, UBUNTU-CVE-2026-53703.