Feb 2026: Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability
CVE-2026-21243 Published on February 10, 2026
Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability
Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an unauthorized attacker to deny service over a network.
Weakness Type
NULL Pointer Dereference
A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions.
Products Associated with CVE-2026-21243
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Affected Versions
Microsoft Windows Server 2019:- Version 10.0.17763.0 and below 10.0.17763.8389 is affected.
- Version 10.0.17763.0 and below 10.0.17763.8389 is affected.
- Version 10.0.20348.0 and below 10.0.20348.4773 is affected.
- Version 10.0.25398.0 and below 10.0.25398.2149 is affected.
- Version 10.0.26100.0 and below 10.0.26100.32370 is affected.
- Version 10.0.26100.0 and below 10.0.26100.32370 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.