CVE-2026-44988 — LibVNCClient Tight Gradient decoding allows malicious server-triggered heap/stack OOB writes
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 th…
Published: 2026-05-27 · CVSS: 8.8 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7