Ubuntu LibVNCServer Severe DoS Vulnerability Information USN-8494-1

ubuntu

July 2, 2026

LibVNCServer could be made to crash or run programs if it received specially crafted network traffic.

Summary

LibVNCServer could be made to crash or run programs if it received

specially crafted network traffic.

Software Description:

- libvncserver: vnc server library

Details:

It was discovered that LibVNCServer incorrectly handled the Tight decoder

in libvncclient. A remote attacker could use this issue to cause

LibVNCServer to crash, resulting in a denial of service, or possibly

execute arbitrary code.

Topics Covered

security advisory critical DoS Ubuntu libvncserver

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 26.04 LTS
  libvncclient1                   0.9.15+dfsg-3ubuntu0.2
  libvncserver1                   0.9.15+dfsg-3ubuntu0.2

Ubuntu 25.10
  libvncclient1                   0.9.15+dfsg-1ubuntu0.2
  libvncserver1                   0.9.15+dfsg-1ubuntu0.2

Ubuntu 24.04 LTS
  libvncclient1                   0.9.14+dfsg-1ubuntu0.2
  libvncserver1                   0.9.14+dfsg-1ubuntu0.2

Ubuntu 22.04 LTS
  libvncclient1                   0.9.13+dfsg-3ubuntu0.2
  libvncserver1                   0.9.13+dfsg-3ubuntu0.2

In general, a standard system update will make all the necessary changes.