CVE catalog

CVE-2026-50538

LibVNCServer vulnerability

Severity: High · CVSS 8.8CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published: Jul 2, 2026, 1:22:47 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.40% · Oct 25, 2026

LibVNCClient is a library for easy implementation of a VNC client. In versions 0.9.12 through 0.9.15, a malicious (or man-in-the-middle) VNC server can force a connecting `libvncclient` to write attacker-controlled data past the end of its framebuffer. This is an out-of-bounds heap write with attacker-controlled length, contents, and offset. It needs no authentication (the attacker is the server), works in a default build with default settings, and fires from a single `FramebufferUpdate` the moment the victim connects. It crashes any client unconditionally (denial of service); we also demonstrated it overwriting an application callback pointer and redirecting execution to attacker-chosen code (code execution) under the default configuration. Commit 540332be3e0acc566fa64da6f1b4680c72c724dd patches the issue.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	libvncserver	sid	`0.9.15+dfsg-6`	fixed
Debian	libvncserver	forky	`0.9.15+dfsg-6`	fixed
Debian	libvncserver	trixie	`0.9.15+dfsg-1+deb13u2`	fixed
Debian	libvncserver	bookworm	`0.9.14+dfsg-1+deb12u2`	fixed
Ubuntu	libvncserver	noble	`0.9.14+dfsg-1ubuntu0.2`	fixed
Ubuntu	libvncclient1	noble	`0.9.14+dfsg-1ubuntu0.2`	fixed
Ubuntu	libvncserver-dev	noble	`0.9.14+dfsg-1ubuntu0.2`	fixed
Ubuntu	libvncserver1	noble	`0.9.14+dfsg-1ubuntu0.2`	fixed
Ubuntu	libvncserver	noble	`0.9.14+dfsg-1+deb12u2`	fixed
Suse	LibVNCServer	linux enterprise server 16.0	`0.9.14-160000.6.1`	fixed
Suse	LibVNCServer	linux enterprise server for sap applications 16.0	`0.9.14-160000.6.1`	fixed
Suse	LibVNCServer	linux enterprise server 12 sp5-ltss	`0.9.9-17.50.1`	fixed
Suse	LibVNCServer	linux enterprise server ltss extended security 12 sp5	`0.9.9-17.50.1`	fixed
Suse	LibVNCServer	linux enterprise module for package hub 15 sp7	`0.9.14-150600.3.12.1`	fixed
Suse	LibVNCServer	linux enterprise workstation extension 15 sp7	`0.9.14-150600.3.12.1`	fixed
Opensuse	LibVNCServer	leap 16.0	`0.9.14-160000.6.1`	fixed
Suse	LibVNCServer	linux enterprise module for package hub 15 sp7	`0.9.10-150000.4.41.1`	fixed
Opensuse	LibVNCServer	tumbleweed	`0.9.15-4.1`	fixed
Ubuntu	libvncserver	22.04	`0.9.13+dfsg-3`	vulnerable
Ubuntu	libvncserver	22.04	`0.9.13+dfsg-3build1`	vulnerable
Ubuntu	libvncserver	22.04	`0.9.13+dfsg-3build2`	vulnerable
Ubuntu	libvncserver	22.04	`0.9.13+dfsg-3ubuntu0.1`	vulnerable
Ubuntu	libvncserver	22.04	`0.9.13+dfsg-3ubuntu0.2`	fixed
Ubuntu	libvncserver	24.04	`0.9.14+dfsg-1`	vulnerable
Ubuntu	libvncserver	24.04	`0.9.14+dfsg-1build1`	vulnerable
Ubuntu	libvncserver	24.04	`0.9.14+dfsg-1build2`	vulnerable
Ubuntu	libvncserver	24.04	`0.9.14+dfsg-1ubuntu0.1`	vulnerable
Ubuntu	libvncserver	24.04	`0.9.14+dfsg-1ubuntu0.2`	fixed
Ubuntu	libvncserver	25.10	`0.9.14+dfsg-1build2`	vulnerable
Ubuntu	libvncserver	25.10	`0.9.15+dfsg-1`	vulnerable
Ubuntu	libvncserver	25.10	`0.9.15+dfsg-1ubuntu0.1`	vulnerable
Ubuntu	libvncserver	25.10	`0.9.15+dfsg-1ubuntu0.2`	fixed
Ubuntu	libvncserver	26.04	`0.9.15+dfsg-1`	vulnerable
Ubuntu	libvncserver	26.04	`0.9.15+dfsg-2`	vulnerable
Ubuntu	libvncserver	26.04	`0.9.15+dfsg-3`	vulnerable
Ubuntu	libvncserver	26.04	`0.9.15+dfsg-3ubuntu0.1`	vulnerable
Ubuntu	libvncserver	26.04	`0.9.15+dfsg-3ubuntu0.2`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	libvncserver	source	sid	`0.9.15+dfsg-6`	not yet assigned	Not reported	[1138253]
Debian	libvncserver	source	forky	`0.9.15+dfsg-6`	not yet assigned	Not reported	[1138253]
Debian	libvncserver	source	trixie	`0.9.15+dfsg-1+deb13u2`	not yet assigned	Not reported	[1138253]
Debian	libvncserver	source	bookworm	`0.9.14+dfsg-1+deb12u2`	not yet assigned	Not reported	[1138253]
Ubuntu	libvncserver	deb	noble	`0.9.14+dfsg-1ubuntu0.2`	Not reported	Not reported	Not reported
Ubuntu	libvncclient1	deb	noble	`0.9.14+dfsg-1ubuntu0.2`	Not reported	Not reported	Not reported
Ubuntu	libvncserver-dev	deb	noble	`0.9.14+dfsg-1ubuntu0.2`	Not reported	Not reported	Not reported
Ubuntu	libvncserver1	deb	noble	`0.9.14+dfsg-1ubuntu0.2`	Not reported	Not reported	Not reported
Ubuntu	libvncserver	deb	noble	`0.9.14+dfsg-1+deb12u2`	Not reported	Not reported	Not reported
Suse	LibVNCServer	rpm	linux enterprise server 16.0	`0.9.14-160000.6.1`	Not reported	SUSE-SU-2026:23601-1	Not reported
Suse	LibVNCServer	rpm	linux enterprise server for sap applications 16.0	`0.9.14-160000.6.1`	Not reported	SUSE-SU-2026:23601-1	Not reported
Suse	LibVNCServer	rpm	linux enterprise server 12 sp5-ltss	`0.9.9-17.50.1`	Not reported	SUSE-SU-2026:4024-1	Not reported
Suse	LibVNCServer	rpm	linux enterprise server ltss extended security 12 sp5	`0.9.9-17.50.1`	Not reported	SUSE-SU-2026:4024-1	Not reported
Suse	LibVNCServer	rpm	linux enterprise module for package hub 15 sp7	`0.9.14-150600.3.12.1`	Not reported	SUSE-SU-2026:4022-1	Not reported
Suse	LibVNCServer	rpm	linux enterprise workstation extension 15 sp7	`0.9.14-150600.3.12.1`	Not reported	SUSE-SU-2026:4022-1	Not reported
Opensuse	LibVNCServer	rpm	leap 16.0	`0.9.14-160000.6.1`	Not reported	OPENSUSE-SU-2026:21735-1	Not reported
Suse	LibVNCServer	rpm	linux enterprise module for package hub 15 sp7	`0.9.10-150000.4.41.1`	Not reported	SUSE-SU-2026:3803-1	Not reported
Opensuse	LibVNCServer	rpm	tumbleweed	`0.9.15-4.1`	Not reported	OPENSUSE-SU-2026:11601-1	Not reported
Ubuntu	libvncserver	deb	22.04	`0.9.13+dfsg-3ubuntu0.2`	Not reported	USN-8494-1	Not reported
Ubuntu	libvncserver	deb	24.04	`0.9.14+dfsg-1ubuntu0.2`	Not reported	USN-8494-1	Not reported
Ubuntu	libvncserver	deb	25.10	`0.9.15+dfsg-1ubuntu0.2`	Not reported	USN-8494-1	Not reported
Ubuntu	libvncserver	deb	26.04	`0.9.15+dfsg-3ubuntu0.2`	Not reported	USN-8494-1	Not reported

[Debian bug #1138253]

OpenFactory catalog packages

[openSUSE Tumbleweed]

[libvncclient1]Unknown
Source package: [LibVNCServer]
Details (1)
- 0.9.15-4.1 · x86_64 · tumbleweed
  Unknown · Fixed: 0.9.15-4.1
  Version impact unknown
  usn · LibVNCServer · opensuse · tumbleweed
[libvncserver1]Unknown
Source package: [LibVNCServer]
Details (1)
- 0.9.15-4.1 · x86_64 · tumbleweed
  Unknown · Fixed: 0.9.15-4.1
  Version impact unknown
  usn · LibVNCServer · opensuse · tumbleweed
[LibVNCServer-devel]Unknown
Source package: [LibVNCServer]
Details (1)
- 0.9.15-4.1 · x86_64 · tumbleweed
  Unknown · Fixed: 0.9.15-4.1
  Version impact unknown
  usn · LibVNCServer · opensuse · tumbleweed

[Debian 12 (Bookworm)]

[libvncclient1]Fixed
Source package: [libvncserver]
Details (2)
- 0.9.14+dfsg-1+deb12u2 · amd64 · bookworm
  Fixed · Fixed: 0.9.14+dfsg-1+deb12u2
  usn · libvncserver · debian · bookworm; usn · libvncserver · debian · 12
- 0.9.14+dfsg-1+deb12u2 · arm64 · bookworm
  Fixed · Fixed: 0.9.14+dfsg-1+deb12u2
  usn · libvncserver · debian · bookworm; usn · libvncserver · debian · 12
[libvncserver1]Fixed
Source package: [libvncserver]
Details (2)
- 0.9.14+dfsg-1+deb12u2 · amd64 · bookworm
  Fixed · Fixed: 0.9.14+dfsg-1+deb12u2
  usn · libvncserver · debian · bookworm; usn · libvncserver · debian · 12
- 0.9.14+dfsg-1+deb12u2 · arm64 · bookworm
  Fixed · Fixed: 0.9.14+dfsg-1+deb12u2
  usn · libvncserver · debian · bookworm; usn · libvncserver · debian · 12
[libvncserver-dev]Fixed
Source package: [libvncserver]
Details (2)
- 0.9.14+dfsg-1+deb12u2 · amd64 · bookworm
  Fixed · Fixed: 0.9.14+dfsg-1+deb12u2
  usn · libvncserver · debian · bookworm; usn · libvncserver · debian · 12
- 0.9.14+dfsg-1+deb12u2 · arm64 · bookworm
  Fixed · Fixed: 0.9.14+dfsg-1+deb12u2
  usn · libvncserver · debian · bookworm; usn · libvncserver · debian · 12

[Debian 13 (Trixie)]

[libvncclient1]Fixed
Source package: [libvncserver]
Details (2)
- 0.9.15+dfsg-1+deb13u2 · amd64 · trixie
  Fixed · Fixed: 0.9.15+dfsg-1+deb13u2
  usn · libvncserver · debian · 13
- 0.9.15+dfsg-1+deb13u2 · arm64 · trixie
  Fixed · Fixed: 0.9.15+dfsg-1+deb13u2
  usn · libvncserver · debian · 13
[libvncserver1]Fixed
Source package: [libvncserver]
Details (2)
- 0.9.15+dfsg-1+deb13u2 · amd64 · trixie
  Fixed · Fixed: 0.9.15+dfsg-1+deb13u2
  usn · libvncserver · debian · 13
- 0.9.15+dfsg-1+deb13u2 · arm64 · trixie
  Fixed · Fixed: 0.9.15+dfsg-1+deb13u2
  usn · libvncserver · debian · 13
[libvncserver-dev]Fixed
Source package: [libvncserver]
Details (2)
- 0.9.15+dfsg-1+deb13u2 · amd64 · trixie
  Fixed · Fixed: 0.9.15+dfsg-1+deb13u2
  usn · libvncserver · debian · 13
- 0.9.15+dfsg-1+deb13u2 · arm64 · trixie
  Fixed · Fixed: 0.9.15+dfsg-1+deb13u2
  usn · libvncserver · debian · 13

Observed: Oct 23, 2026, 9:44:35 PM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [SUSE security advisories and VEX] · [Ubuntu Security Notices (USN)]