[USN-8494-1] LibVNCServer vulnerability

[noreply+usn-bot at canonical.com]

==========================================================================
Ubuntu Security Notice USN-8494-1
July 02, 2026

libvncserver vulnerability
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 26.04 LTS
- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS

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.

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.

References:
  https://ubuntu.com/security/notices/USN-8494-1
  CVE-2026-50538

Package Information:
  https://launchpad.net/ubuntu/+source/libvncserver/0.9.15+dfsg-3ubuntu0.2
  https://launchpad.net/ubuntu/+source/libvncserver/0.9.15+dfsg-1ubuntu0.2
  https://launchpad.net/ubuntu/+source/libvncserver/0.9.14+dfsg-1ubuntu0.2
  https://launchpad.net/ubuntu/+source/libvncserver/0.9.13+dfsg-3ubuntu0.2
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