CVE-2019-25600: Uvnc Ultravnc Viewer

Medium severity, CVSS 6.5. EPSS: 0.7% chance of exploitation in the next 30 days.

UltraVNC Viewer 1.2.2.4 contains a denial of service vulnerability that allows attackers to crash the application by supplying an oversized string to the VNC Server input field. Attackers can paste a malicious string containing 256 repeated characters into the VNC Server field and click Connect to trigger a buffer overflow that crashes the viewer.

Affected products

• Uvnc Ultravnc Viewer: version 1.2.2.4 only

Published 2026-03-22. Last modified 2026-06-17.