CVE-2026-44988
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
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2026-44988
Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2026-44988.html
Mitigation details
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
Apply commands
https://github.com/LibVNC/libvncserver/security/advisories/GHSA-jcc5-8wj4-7c58https://github.com/LibVNC/libvncserver/commit/5b270544b85233668b98161323297d418a8f5fd1OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| sles | affected | | |
| debian | bookworm | affected | |
| debian | bullseye | affected | |
| debian | forky | affected | |
| debian | sid | affected | |
| debian | trixie | affected | |
References
CWEs
CWE-787
Verify integrity in audit chain (admin only). AS-IS.