CVE-2026-44041: uvnc ultravnc Out-of-bounds Read

Vulnerability summary

CVE-2026-44041 is a medium (CVSS 6.5) Out-of-bounds Read vulnerability in uvnc ultravnc. EPSS estimates a 0.41% chance of exploitation in the next 30 days, higher than 34.2% of scored vulnerabilities.

Timeline

1. 01-07-2026
   PublishedVulnerability first disclosed.
2. 09-07-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.