Home / mailings

PDF

[USN-8463-1] LibVNCServer vulnerabilities

Posted on 23 June 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8463-1
June 23, 2026

libvncserver vulnerabilities
==========================================================================
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:

Several security issues were fixed in LibVNCServer.

Software Description:
- libvncserver: vnc server library

Details:

It was discovered that LibVNCServer had a memory leak in the client cleanup
function. An attacker could possibly use this issue to cause LibVNCServer
to consume memory, leading to a denial of service. This issue only affected
Ubuntu 22.04 LTS. (CVE-2020-29260)

It was discovered that LibVNCServer did not properly validate bounds when
handling UltraZip encoding subrectangles. A remote attacker could possibly
use this issue to obtain sensitive information or cause a denial of
service. This issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and
Ubuntu 25.04. (CVE-2026-32853)

It was discovered that LibVNCServer did not properly validate return values
in the HTTP proxy handlers. A remote attacker could possibly use this issue
to cause LibVNCServer to crash, resulting in a denial of service. This
issue only affected Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 25.04.
(CVE-2026-32854)

It was discovered that LibVNCServer did not properly handle Tight encoding
gradient filter rectangles. A remote attacker could use this issue to cause
LibVNCServer to crash, resulting in a denial of service, or possibly
execute arbitrary code. (CVE-2026-44988)

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-3ubuntu0.1
libvncserver1 0.9.15+dfsg-3ubuntu0.1

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

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

Ubuntu 22.04 LTS
libvncclient1 0.9.13+dfsg-3ubuntu0.1
libvncserver1 0.9.13+dfsg-3ubuntu0.1

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

References:
https://ubuntu.com/security/notices/USN-8463-1
CVE-2020-29260, CVE-2026-32853, CVE-2026-32854, CVE-2026-44988

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

--===============1861192851558423535==Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature

 

TOP