CVE-2026-59691 PUBLISHED

Gstreamer: gstreamer: rfbsrc/librfb hextile heap out-of-bounds write with 16bpp framebuffer

Assigner: redhat
Reserved: 06.07.2026 Published: 09.07.2026 Updated: 09.07.2026

A heap buffer overflow vulnerability was found in GStreamer's rfbsrc plugin. When a client connects to a malicious RFB/VNC server that advertises a 16bpp framebuffer and sends Hextile-encoded updates, the Hextile background fill path writes 32-bit pixel values into a buffer allocated for 16-bit pixels. This type mismatch causes an out-of-bounds heap write that can lead to denial of service (process crash) and potential memory corruption.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H
CVSS Score: 7.1

Product Status

Vendor Red Hat
Product Red Hat Enterprise Linux 10
Versions Default: affected
Vendor Red Hat
Product Red Hat Enterprise Linux 6
Versions Default: affected
Vendor Red Hat
Product Red Hat Enterprise Linux 7
Versions Default: affected
Vendor Red Hat
Product Red Hat Enterprise Linux 7
Versions Default: affected
Vendor Red Hat
Product Red Hat Enterprise Linux 8
Versions Default: affected
Vendor Red Hat
Product Red Hat Enterprise Linux 9
Versions Default: affected

Workarounds

There is no complete mitigation for this vulnerability. The following measures can reduce risk:

  1. Do not connect GStreamer pipelines using rfbsrc to untrusted or unknown VNC servers.
  2. If the rfbsrc plugin is not required, remove the librfb plugin shared object from the GStreamer plugins directory (typically /usr/lib64/gstreamer-1.0/libgstrfbsrc.so).
  3. Network-level controls (firewall rules) can restrict outbound VNC connections to trusted servers only.

Credits

  • Red Hat would like to thank Clouditera Security (Clouditera), NSFOCUS (NSFOCUS), and Z.ai Security (Z.ai) for reporting this issue.

References

Problem Types

  • Out-of-bounds Write CWE