NULL pointer dereference in Microsoft Windows Server 2019
CVE-2026-21243
Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an unauthorized attacker to deny service over a network.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.014 (71.8th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 72nd percentile — 71.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.013 · newest: 0.014 · change: +0.001
Affected products
- Microsoft Windows Server 2019 — versions 10.0.17763.0
- Microsoft Windows Server 2019
- Microsoft Windows Server 2019 (Server Core Installation) — versions 10.0.17763.0
- Microsoft Windows Server 2022 — versions 10.0.20348.0
- Microsoft Windows Server 2022
- Microsoft Windows Server 2022 23h2
- Microsoft Windows Server 2022, 23h2 Edition (Server Core Installation) — versions 10.0.25398.0
- Microsoft Windows Server 2025 — versions 10.0.26100.0
- Microsoft Windows Server 2025
- Microsoft Windows Server 2025 (Server Core Installation) — versions 10.0.26100.0
Weakness classification (CWE)
References
- Windows Lightweight Directory Access Protocol (LDAP) Denial of Service Vulnerability (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-21243?
- CVE-2026-21243 is a high-severity vulnerability in Microsoft Windows Server 2019, classified under NULL Pointer Dereference. CVSS score: 7.5/10. Published 2026-02-10.
- How severe is CVE-2026-21243?
- High severity. CVSS v3 base score is 7.5 out of 10.