USN-8463-1: LibVNCServer vulnerabilities

Publication date

23 June 2026

Overview

Several security issues were fixed in LibVNCServer.


Packages

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,...

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

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

Learn more about how to get the fixes.

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


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