DEBIAN-CVE-2026-50538

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Source
https://security-tracker.debian.org/tracker/CVE-2026-50538
Import Source
https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-50538.json
JSON Data
https://api.test.osv.dev/v1/vulns/DEBIAN-CVE-2026-50538
Upstream
Published
2026-08-21T21:16:59Z
Modified
2026-09-01T16:06:48Z
Severity
  • 8.8 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H CVSS Calculator
Summary
[none]
Details

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.

References

Affected packages

Debian:12 / libvncserver

Package

Name
libvncserver
Purl
pkg:deb/debian/libvncserver?arch=source&distro=bookworm

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
0.9.14+dfsg-1+deb12u2

Affected versions

0.*
0.9.14+dfsg-1
0.9.14+dfsg-1+deb12u1

Ecosystem specific 

{
    "urgency":  "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-50538.json"

Debian:13 / libvncserver

Package

Name
libvncserver
Purl
pkg:deb/debian/libvncserver?arch=source&distro=trixie

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
0.9.15+dfsg-1+deb13u2

Affected versions

0.*
0.9.15+dfsg-1
0.9.15+dfsg-1+deb13u1

Ecosystem specific 

{
    "urgency":  "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-50538.json"

Debian:14 / libvncserver

Package

Name
libvncserver
Purl
pkg:deb/debian/libvncserver?arch=source&distro=forky

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
0.9.15+dfsg-6

Affected versions

0.*
0.9.15+dfsg-1
0.9.15+dfsg-2
0.9.15+dfsg-3
0.9.15+dfsg-4
0.9.15+dfsg-5

Ecosystem specific 

{
    "urgency":  "not yet assigned"
}

Database specific

source 
"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-50538.json"