CVE-2026-44041 UltraVNC vncWc2Mb calls wcslen() before validating that the wide string is NUL-terminated

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...

CVE-2026-44041 UltraVNC vncWc2Mb calls wcslen() before validating that the wide string is NUL-terminated

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...

EUVD-2026-40878

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...

CVE-2026-44041

UltraVNC

CVE-2026-44042

UltraVNC repeater up to version 1.8.2.2 contains an off-by-one bug in the Base64 decode helper used for HTTP Basic authentication. In repeater/webgui/webutils.c:817, wi_uudecode() uses a strict > check to ensure output fits the buffer, but the correct condition is >=. When strlen(authdata) ...

CVE-2026-44042 UltraVNC repeater wi_uudecode off-by-one in base64 decode boundary check

UltraVNC repeater through 1.8.2.2 contains an off-by-one error in the Base64 decode helper used for HTTP Basic authentication. In repeater/webgui/webutils.c:817, the wiuudecode function checks whether the input length exceeds the output buffer with a strict greater-than comparison , while the...

EUVD-2026-40877

UltraVNC repeater through 1.8.2.2 contains an off-by-one error in the Base64 decode helper used for HTTP Basic authentication. In repeater/webgui/webutils.c:817, the wiuudecode function checks whether the input length exceeds the output buffer with a strict greater-than comparison , while the...

CVE-2026-44042 UltraVNC repeater wi_uudecode off-by-one in base64 decode boundary check

UltraVNC repeater through 1.8.2.2 contains an off-by-one error in the Base64 decode helper used for HTTP Basic authentication. In repeater/webgui/webutils.c:817, the wiuudecode function checks whether the input length exceeds the output buffer with a strict greater-than comparison , while the...

CVE-2026-44042

UltraVNC repeater through 1.8.2.2 contains an off-by-one error in the Base64 decode helper used for HTTP Basic authentication. In repeater/webgui/webutils.c:817, the wiuudecode function checks whether the input length exceeds the output buffer with a strict greater-than comparison , while the...

PT-2026-54490

Name of the Vulnerable Software and Affected Versions UltraVNC repeater versions prior to 1.8.2.3 Description The embedded HTTP administration server contains a global buffer overflow. The functions wi senderr and wi replyhdr in repeater/webgui/webutils.c write the HTTP request URI into a fixed...

PT-2026-54485

UltraVNC repeater through 1.8.2.2 contains a post-authentication out-of-bounds write in the allow/deny rule parser. In repeater/webgui/settings.c:225-272, after strncpy s copies a rule token into temp1rule1 25-byte destination or temp2/temp3 16-byte destination, the code unconditionally writes a...

PT-2026-54489

UltraVNC repeater through 1.8.2.2 initializes the HTTP administration server with a hardcoded default password. In repeater/webgui/settings.c:197, when settings2.txt is absent on first run the repeater writes the literal string "adminadmi2" as the admin password via strcpy ssaved password, 64,...

PT-2026-54478

Name of the Vulnerable Software and Affected Versions UltraVNC versions prior to 1.8.2.3 Description An out-of-bounds read exists in the wide-string to multibyte conversion helper. The vncWc2Mb function in rfb/dh.cpp:204 passes a caller-supplied WCHAR pointer to wcslen without performing a bounds...

PT-2026-54487

Name of the Vulnerable Software and Affected Versions UltraVNC viewer versions prior to 1.8.2.3 Description An off-by-one stack buffer overflow exists in the RFB ServerInit message handler within the vncviewer/ClientConnection.cpp file. When a server-supplied nameLength is exactly 2024, the...

PT-2026-54477

Name of the Vulnerable Software and Affected Versions UltraVNC versions prior to 1.8.2.3 Description The software uses a cryptographically weak pseudo-random number generator to produce VNC authentication challenge bytes. Specifically, the vncRandomBytes function seeds libc rand using a combinati...

PT-2026-54479

Name of the Vulnerable Software and Affected Versions UltraVNC repeater versions prior to 1.8.2.3 Description An off-by-one error exists in the Base64 decode helper used for HTTP Basic authentication. The wi uudecode function in the file repeater/webgui/webutils.c uses a strict greater-than...

PT-2026-54486

Name of the Vulnerable Software and Affected Versions UltraVNC versions prior to 1.8.2.3 Description Inadequate cryptography in the MS-Logon II authentication scheme rfbUltraVNC MsLogonIIAuth allows a network attacker to disclose credentials. In the file rfb/dh.cpp, the Diffie-Hellman key exchang...

CVE-2026-4962

A security flaw has been discovered in UltraVNC up to 1.6.4.0. Affected by this issue is some unknown functionality in the library version.dll of the component Service. The manipulation results in uncontrolled search path. The attack needs to be approached locally. This attack is characterized by...

EUVD-2026-16725

A security flaw has been discovered in UltraVNC up to 1.6.4.0. Affected by this issue is some unknown functionality in the library version.dll of the component Service. The manipulation results in uncontrolled search path. The attack needs to be approached locally. This attack is characterized by...

CVE-2026-4962

A security flaw has been discovered in UltraVNC up to 1.6.4.0. Affected by this issue is some unknown functionality in the library version.dll of the component Service. The manipulation results in uncontrolled search path. The attack needs to be approached locally. This attack is characterized by...