CVE-2026-44988

high

Published 2026-05-27 · Modified 2026-06-01

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CVSS v3

8.8

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS v4 NEW

—

not yet in upstream

VIR risk

8.8

Description

LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.

Predictions

Exploit likelihood

92%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

Mitigation details

Source: Debian Security Tracker · View original ↗ · DFSG

CVE-2026-44988 NameCVE-2026-44988 DescriptionLibVNCClient is a library for easy implementation of a VNC client. In ... SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) Vulnerable and fixed packages The table below lists information on source packages. Source PackageReleaseVersionStatus…

CVE-2026-44988

Name	CVE-2026-44988
Description	LibVNCClient is a library for easy implementation of a VNC client. In ...
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
libvncserver (PTS)	bullseye	0.9.13+dfsg-2+deb11u1	vulnerable
	bookworm	0.9.14+dfsg-1+deb12u1	vulnerable
	trixie	0.9.15+dfsg-1+deb13u1	vulnerable
	forky, sid	0.9.15+dfsg-4	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
libvncserver	source	(unstable)	(unfixed)

Notes

https://github.com/LibVNC/libvncserver/security/advisories/GHSA-jcc5-8wj4-7c58
https://github.com/LibVNC/libvncserver/commit/5b270544b85233668b98161323297d418a8f5fd1

Home - Debian Security - Source (Git)

Apply commands

text fix

Notes

https://github.com/LibVNC/libvncserver/security/advisories/GHSA-jcc5-8wj4-7c58https://github.com/LibVNC/libvncserver/commit/5b270544b85233668b98161323297d418a8f5fd1

OS impact

SUSE Affected 1 release

Version	Status	Fixed in
—	Affected	—

Debian Mixed 5 releases

Version	Status	Fixed in
trixie	Affected	—
sid	Fixed	`0.9.15+dfsg-5`
forky	Fixed	`0.9.15+dfsg-5`
bullseye	Affected	—
bookworm	Affected	—

References

CWEs

CWE-787

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.