CVE-2026-7830 UltraVNC MS-Logon II uses 64-bit Diffie-Hellman and seeded libc rand() enabling credential interception

UltraVNC through 1.8.2.2 uses inadequate cryptography in the MS-Logon II authentication scheme rfbUltraVNCMsLogonIIAuth. In rfb/dh.cpp the Diffie-Hellman key exchange is performed with parameters that fit in an unsigned 64-bit integer DHMAXBITS controls the prime size. A 64-bit DH key can be brok...

CVE-2026-7830

CVE-2026-7830 affects UltraVNC up to version 1.8.2.2 and concerns the MS-Logon II authentication. The DH key exchange uses parameters within 64-bit space (DH_MAX_BITS) and the private exponent is generated using a rng() that relies on three libc rand() calls seeded from time(NULL). This yields an...

CVE-2026-7830 UltraVNC MS-Logon II uses 64-bit Diffie-Hellman and seeded libc rand() enabling credential interception

UltraVNC through 1.8.2.2 uses inadequate cryptography in the MS-Logon II authentication scheme rfbUltraVNCMsLogonIIAuth. In rfb/dh.cpp the Diffie-Hellman key exchange is performed with parameters that fit in an unsigned 64-bit integer DHMAXBITS controls the prime size. A 64-bit DH key can be brok...

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...

Authentication flaw

The MS-Logon authentication scheme in UltraVNC aka Ultr@VNC 1.0.1 uses weak encryption XOR for challenge/response, which allows remote attackers to gain privileges by sniffing and decrypting passwords...

CVE-2006-2206

The CVE-2006-2206 entry concerns UltraVNC 1.0.1 whose MS-Logon scheme uses weak XOR encryption for challenge/response. This weak cryptography permits an attacker on the network to sniff credentials and decrypt passwords, enabling privilege escalation.

CVE-2006-2206

The MS-Logon authentication scheme in UltraVNC aka Ultr@VNC 1.0.1 uses weak encryption XOR for challenge/response, which allows remote attackers to gain privileges by sniffing and decrypting passwords...

Vulnerability in the way [email protected] handles MS-Logon Authentication.

AGR IT Advisory May 2, 2006 AGR-ADV-2006-01 TITLE: Vulnerability in the way [email protected] handles MS-Logon Authentication. Overview Deon Force discovered a vulnerability in Ultr@VNC 1.0.1 and earlier versions with MS-Logon I and MS-Logon II authentication that may allow attackers to crack the...