CVE-2026-21243: Microsoft Windows Server 2019

High severity, CVSS 7.5. EPSS: 1.4% chance of exploitation in the next 30 days.

Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an unauthorized attacker to deny service over a network.

Affected products

• Microsoft Windows Server 2019: before 10.0.17763.8389 (fixed in 10.0.17763.8389)
• Microsoft Windows Server 2022: before 10.0.20348.4711 (fixed in 10.0.20348.4711)
• Microsoft Windows Server 2022 23h2: before 10.0.25398.2149 (fixed in 10.0.25398.2149)
• Microsoft Windows Server 2025: before 10.0.26100.32313 (fixed in 10.0.26100.32313)

Published 2026-02-10. Last modified 2026-06-17.