CVE-2026-128321 Tight JPEG decoding in TightVNC and UltraVNC viewers contains a heap-based buffer overflow vulnerability

The TightVNC and UltraVNC viewers are susceptible to a heap-based buffer overflow within the Tight JPEG decoding component. The vulnerability exists because the software fails to validate an attacker-controlled framebuffer rectangle width against a fixed-size decoding buffer. A malicious VNC serv...