CVE-2026-44041: Uvnc Ultravnc

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

UltraVNC through 1.8.2.2 contains an out-of-bounds read in the wide-string to multibyte conversion helper. In rfb/dh.cpp:204, the vncWc2Mb() function passes a caller-supplied WCHAR pointer to wcslen() before any bounds check. If the caller provides a wide-character buffer that is not properly NUL-terminated, wcslen() reads past the end of the buffer until it encounters a NUL wchar, resulting in an out-of-bounds read. Under typical Win32 API usage this requires an abnormal caller contract. Impact is limited to a potential information disclosure from adjacent memory regions or a process crash (denial of service) if the over-read crosses a page boundary.

Affected products

• Uvnc Ultravnc: up to and including 1.8.2.2

Published 2026-07-01. Last modified 2026-07-09.