CVE-2026-21251
published 2026-02-10CVE-2026-21251: Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally.
PriorityP346high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.42%
33.8th percentile
Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally.
Affected
14 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| microsoft | windows_server_2016 | < 10.0.14393.8868 | 10.0.14393.8868 |
| microsoft | windows_server_2016 | >= 10.0.14393.0 < 10.0.14393.8868 | 10.0.14393.8868 |
| microsoft | windows_server_2019 | < 10.0.17763.8389 | 10.0.17763.8389 |
| microsoft | windows_server_2019 | >= 10.0.17763.0 < 10.0.17763.8389 | 10.0.17763.8389 |
| microsoft | windows_server_2022 | < 10.0.20348.4711 | 10.0.20348.4711 |
| microsoft | windows_server_2022 | >= 10.0.20348.0 < 10.0.20348.4773 | 10.0.20348.4773 |
| microsoft | windows_server_2022_23h2 | < 10.0.25398.2149 | 10.0.25398.2149 |
| microsoft | windows_server_2025 | < 10.0.26100.32313 | 10.0.26100.32313 |
| microsoft | windows_server_2025 | >= 10.0.26100.0 < 10.0.26100.32370 | 10.0.26100.32370 |
| msrc | windows_server_2016 | — | — |
| msrc | windows_server_2019 | — | — |
| msrc | windows_server_2022 | — | — |
| msrc | windows_server_2022_23h2_edition | — | — |
| msrc | windows_server_2025 | — | — |
CVSS provenance
nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_msrc7.8HIGH
Stop checking back — get the weekly exploitation signal.
Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.
GHSA
GHSA-6q2h-rrfg-fm75: Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally
ghsa_unreviewed·2026-02-10
CVE-2026-21251 [HIGH] CWE-416 GHSA-6q2h-rrfg-fm75: Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally
Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally.
Microsoft
Cluster Client Failover (CCF) Elevation of Privilege Vulnerability
vendor_msrc·2026-02-10·CVSS 7.8
CVE-2026-21251 [HIGH] CWE-416 Cluster Client Failover (CCF) Elevation of Privilege Vulnerability
Cluster Client Failover (CCF) Elevation of Privilege Vulnerability
Description: Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally.
FAQ: What privileges could be gained by an attacker who successfully exploited this vulnerability?
An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.
Windows Cluster Client Failover: Windows Cluster Client Failover
Microsoft: Microsoft
Customer Action Required: Yes
Impact: Elevation of Privilege
Exploit Status: Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation Unlikely
Reference: https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB5075904
Reference: https://support.microsoft.com/help/5075904
Reference: https://catalog.update.
No detection rules found.
No public exploits indexed.
Sophos
February’s Patch Tuesday assumes battle stations
blogs_sophos·2026-02-13
February’s Patch Tuesday assumes battle stations
Akuter Cyberangriff? Fordern Sie Sofort-Hilfe an
Sophos Central
Partner-Portal
Lizenzen & Accounts
Sophos Home
Sophos Central
Sophos-Central-Anmeldung
Sophos KI
Integrationen
Threat Intelligence
Testversion
Endpoint Protection (Next-Gen Antivirus)
EDR – Endpoint Detection and Response
Server Protection
Mobile Security
XDR – Extended Detection and Response
XDR mit Next-Gen SIEM
ITDR – Identity Threat Detection and Response
Next-Gen Firewall (NGFW)
NDR – Network Detection and Response
Netzwerk-Switches
Wireless Access Points
Workspace Protection
Protected Browser
Zero Trust Network Access (ZTNA)
DNS Protection
Email Monitoring System
E-Mail- und Phishing-Schutz
Awareness-Training für Mitarbeitende
Schutz für Cloud Workloads
Cloud Security Posture Management (CSP
Bleepingcomputer
Microsoft February 2026 Patch Tuesday fixes 6 zero-days, 58 flaws
blogs_bleepingcomputer·2026-02-10·CVSS 8.8
[HIGH] Microsoft February 2026 Patch Tuesday fixes 6 zero-days, 58 flaws
## Microsoft February 2026 Patch Tuesday fixes 6 zero-days, 58 flaws
## Lawrence Abrams
25 Elevation of Privilege vulnerabilities
5 Security Feature Bypass vulnerabilities
12 Remote Code Execution vulnerabilities
6 Information Disclosure vulnerabilities
3 Denial of Service vulnerabilities
7 Spoofing vulnerabilities
When BleepingComputer reports on Patch Tuesday security updates, we only count those released by Microsoft today. Therefore, the number of flaws does not include 3 Microsoft Edge flaws fixed earlier this month.
As part of these updates, Microsoft has also begun to roll out updated Secure Boot certificates to replace the original 2011 certificates that are expiring in late June 2026.
"With this update, Windows quality updates include a broad set of targeting data that i
Wiz
CVE-2026-21251 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 7.8
CVE-2026-21251 [HIGH] CVE-2026-21251 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-21251 :
vulnerability analysis and mitigation
Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally.
Source : NVD
## 7.8
Score
Published February 10, 2026
Severity HIGH
CNA Score 7.8
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 9.7
Exploitation Probability (EPSS) N/A
Sources
NVD
## Get a CVE risk assessment
Get a prioritized view of CVEs in your cloud—so you can focus on what's exploitable, not just what's listed.
Free Vulnerability Assessment
## Benchmark your Cloud Security Posture
Evaluate your cloud security practices across 9 security domains to benchmark your risk level and identify gaps in your defe
Sophos
February’s Patch Tuesday assumes battle stations
blogs_sophos
February’s Patch Tuesday assumes battle stations
Share This
Microsoft on Tuesday released 58 patches affecting 15 product families. Five of the addressed issues, all involving Azure, are considered by Microsoft to be of Critical severity, though only two require urgent attention (more on that below). Fifteen have a CVSS base score of 8.0 or higher, including two with a 9.8 base score. Six are known to be under active exploit in the wild, and three are publicly disclosed (including one not yet known to be under exploit).
At patch time, five CVEs are judged more likely to be exploited in the next 30 days by the company’s estimation, in addition to the six already detected to be so. Various of this month’s issues are amenable to direct detection by Sophos protections, and we include information on those in a table below. The release also
2026-02-10
Published