CVE-2025-26633 — Windows 10 21h2
HIGHCVE-2025-26633 is a high-severity (CVSS 7) CWE-707 vulnerability in microsoft windows 10 21h2. It is in CISA's Known Exploited Vulnerabilities catalog (added 2025-03-11) and has been used in ransomware campaigns — treat it as actively exploited and patch now. A fix is available — see the affected versions and patch details below.
Improper neutralization in Microsoft Management Console allows an unauthorized attacker to bypass a security feature locally.
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2025-03-11 — including use in ransomware campaigns. Federal agencies were required to remediate by 2025-04-01.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2025-26633.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2025-26633 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 394,803 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Counts from FIRST.org, log-scaled.
Description
Improper neutralization in Microsoft Management Console allows an unauthorized attacker to bypass a security feature locally.
Affected Products
windows 10 21h2microsoftwindows 10 22h2microsoftwindows 10 1507microsoftwindows 10 1607microsoftwindows 10 1809microsoftwindows 11 22h2microsoftResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Microsoft MMC MSC EvilTwin - Local Admin Creation
by Mohammed Idrees Banyamer · Apr 8, 2026
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every microsoft windows 10 21h2 deployment and check each version against the affected-products list above.
Fix
Apply the microsoft windows 10 21h2 security patch or hotfix for CVE-2025-26633 on the affected version, following the vendor advisory for your exact build.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
Frequently Asked Questions
Is CVE-2025-26633 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.