CVE-2026-107611

Name of the Vulnerable Software and Affected Versions GlavSoft TightVNC Viewer for Windows versions prior to 2.8.88

Description An out-of-bounds read issue exists in the ZRLE decoder. A malicious or compromised VNC server can trigger this by sending ZRLE-encoded tiles with palette indices that exceed the declared palette size. The functions readPaletteRleTile() and readPackedPaletteTile() use the attacker-supplied index to look up colors without validating it against the palette size. This results in out-of-bounds heap data being copied into the framebuffer, causing a garbled display, or causing a read fault that crashes the viewer.

Recommendations Update GlavSoft TightVNC Viewer for Windows to version 2.8.88 or later.