Vulnerability · Published Feb 10, 2026 · Assigned by microsoft
CVE-2026-21243Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability
High 7.5
In plain English
A high-severity null pointer dereference in Windows Server 2019 from Microsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.4% (higher than 73% of all known vulnerabilities).
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)1.4%top 27.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an unauthorized attacker to deny service over a network.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows Server 2019 | 10.0.17763.0 – before 10.0.17763.8389 |
| Microsoft | Windows Server 2019 (Server Core installation) | 10.0.17763.0 – before 10.0.17763.8389 |
| Microsoft | Windows Server 2022 | 10.0.20348.0 – before 10.0.20348.4773 |
| Microsoft | Windows Server 2022, 23H2 Edition (Server Core installation) | 10.0.25398.0 – before 10.0.25398.2149 |
| Microsoft | Windows Server 2025 | 10.0.26100.0 – before 10.0.26100.32370 |
| Microsoft | Windows Server 2025 (Server Core installation) | 10.0.26100.0 – before 10.0.26100.32370 |
Weakness: CWE-476 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C
References
- Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability vendor-advisory, patch