The Winsock2ProtocolCatalogMutex mutex in Windows NT 4.0 has inappropriate Everyone/Full Control permissions, which allows local users to modify the permissions to "No Access" and disable Winsock network connectivity to cause a denial of service, aka the "Winsock Mutex" vulnerability.
Severity
CVSS 3.1
7.1 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
EPSS
3.0% chance of exploitation in the next 30 days; higher than 87% of CVEs (scores of 2026-10-31)