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

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-15 · updated 2026-08-05
Weakness: CWE-125

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.

Affected products

Red Hat Enterprise Linux 10: all versions — fixed in 0:1.26.7-2.el10_2.1
Red Hat Enterprise Linux 10.0 Extended Update Support: all versions — fixed in 0:1.24.11-1.el10_0.2
Red Hat Enterprise Linux 9: all versions — fixed in 0:1.22.12-6.el9_8.1
Red Hat Enterprise Linux 9.6 Extended Update Support: all versions — fixed in 0:1.22.12-4.el9_6.1

How to fix

Upgrade to a fixed version: Red Hat Enterprise Linux 10 0:1.26.7-2.el10_2.1; Red Hat Enterprise Linux 10.0 Extended Update Support 0:1.24.11-1.el10_0.2; Red Hat Enterprise Linux 9 0:1.22.12-6.el9_8.1; Red Hat Enterprise Linux 9.6 Extended Update Support 0:1.22.12-4.el9_6.1. Check the vendor advisory for mitigations.

References

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