CVE-2026-128321

Not enough EPSS history yet.

Tight JPEG decoding in TightVNC and UltraVNC viewers contains a heap-based buffer overflow because an attacker-controlled framebuffer rectangle width is not validated against a fixed-size decoding buffer. A malicious VNC server can cause an out-of-bounds heap write when a user connects, resulting in application crash and potentially other memory-corruption impacts.

• github.comhttps://github.com/ultravnc/ultravnc
• www.tightvnc.comhttps://www.tightvnc.com/
• www.kb.cert.orghttps://www.kb.cert.org/vuls/id/644655

No related CVEs by CWE or product.