Junglewise Threat Intelligence

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

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

Technologies: Gstreamer Gst-Plugins-Bad. Vendors: Gstreamer, Red Hat.

Executive brief

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.

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

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