# CVE-2026-59691: GStreamer rfbsrc heap buffer overflow in Hextile decoding

Source: https://junglewise.ai/threats/cve-2026-59691-gstreamer-rfbsrc-heap-buffer-overflow-in-hextile-decoding  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-09. Updated: 2026-07-09  
License: CC BY 4.0 with a link back

CVE-2026-59691 · Severity: high · CVSS 7.1 · Published 2026-07-09

A security vulnerability exists in GStreamer, a widely used multimedia framework, specifically within its VNC/RFB connection plugin. If a user connects to a malicious VNC server using this software, the server can send specially crafted video updates that cause the application to crash or corrupt its memory. This could lead to a denial of service or potentially allow an attacker to compromise the integrity of the system running the GStreamer application.

Technologies: [Gstreamer Gst-Plugins-Bad](https://junglewise.ai/threats/technologies/gst-plugins-bad). Vendors: [Gstreamer](https://junglewise.ai/threats/vendors/gstreamer), [Red Hat](https://junglewise.ai/threats/vendors/red-hat).

## Quick answers

**Is CVE-2026-59691 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-59691 being exploited in the wild.

**How severe is CVE-2026-59691?** High severity, with a CVSS score of 7.1, published 9 July 2026.

**Which products and versions are affected?** Gstreamer Gst-Plugins-Bad Red Hat Enterprise Linux 6, 7, 8, 9, 10; Red Hat GStreamer gst-plugins-bad-free Red Hat Enterprise Linux 6, 7, 8, 9, 10.

**Is there a fix for CVE-2026-59691?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-59691 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-59691?** Check whether you run Gstreamer Gst-Plugins-Bad or Red Hat GStreamer gst-plugins-bad-free at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A heap buffer overflow vulnerability exists in GStreamer's rfbsrc plugin (specifically within the librfb component) due to a type mismatch in the rfb_decoder_fill_rectangle() function. When a client connects to a malicious RFB/VNC server advertising a 16bpp (bits per pixel) framebuffer, the Hextile background fill path incorrectly casts a 16-bit destination buffer to a 32-bit pointer (guint32*). This causes the decoder to write 32-bit pixel values into memory allocated for 16-bit pixels, leading to an out-of-bounds heap write. An attacker can exploit this by hosting a malicious VNC server and enticing a user to connect via GStreamer, resulting in a process crash or potential memory corruption. A fix is planned for GStreamer version 1.28.5.

## Affected products

- Red Hat GStreamer gst-plugins-bad-free Red Hat Enterprise Linux 6, 7, 8, 9, 10
- GStreamer gst-plugins-bad 1.28.3

## Timeline

- 2026-07-06: disclosed: Reported by OSIDB Bzimport
- 2026-07-09: advisory: NVD and Red Hat published advisory details

## References

- [https://access.redhat.com/downloads/content/package-browser/](https://access.redhat.com/downloads/content/package-browser/)
- [https://access.redhat.com/security/cve/CVE-2026-59691](https://access.redhat.com/security/cve/CVE-2026-59691)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2497343](https://bugzilla.redhat.com/show_bug.cgi?id=2497343)
- [https://gitlab.freedesktop.org/gstreamer/gstreamer-security/-/merge_requests/100](https://gitlab.freedesktop.org/gstreamer/gstreamer-security/-/merge_requests/100)
- [https://gitlab.freedesktop.org/gstreamer/gstreamer/-/work_items/5173](https://gitlab.freedesktop.org/gstreamer/gstreamer/-/work_items/5173)

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