CVE-2026-21243
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
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.
- Record
CVE-2026-21243- CVSS 3.1
- 7.5 High
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 - Weakness
- CWE-476
- Updated
- 2026-11-02
EUVDEUVD-2026-7317
Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an unauthorized attacker to deny service over a network.
- Record
EUVD-2026-7317- CVSS 3.1
- 7.5 High
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-843x-gmwc-22g8
Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an...
Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an unauthorized attacker to deny service over a network.
- Record
GHSA-843x-gmwc-22g8- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-476
- Updated
- 2026-11-02
NVD
Null pointer dereference in Windows LDAP - Lightweight Directory Access Protocol allows an unauthorized attacker to deny service over a network.
- Record
CVE-2026-21243- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-476
- Updated
- 2026-11-02
Affected products
- microsoft windows server 2019
- microsoft windows server 2019 (server core installation)
- microsoft windows server 2022
- microsoft windows server 2022, 23h2 edition (server core installation)
- microsoft windows server 2025
- microsoft windows server 2025 (server core installation)
- microsoft windows server 2022 23h2
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-21243 is a high vulnerability (CVSS 7.5) in Microsoft Windows Server 2019, published February 10, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.41%, the 73rd percentile. No source names a fixed version.