Known exploited · Microsoft
CVE-2021-41357: Microsoft Win32k Privilege Escalation Vulnerability
What it is
Microsoft Win32k contains an unspecified vulnerability that allows for privilege escalation.
- Vendor
- Microsoft
- Product
- Win32k
- Added to KEV
- April 25, 2022
- CISA due date
- May 16, 2022
- Ransomware use
- Unknown
- Weakness
- Not mapped by CISA
What CISA requires
Apply updates per vendor instructions.
Forensic triage
No
What to do now
- Find every instance of Win32k you run, including the forgotten ones, and check its version against the vendor advisory.
- Apply the vendor's fix or mitigation, before May 16, 2022 if you are bound by CISA's deadline, sooner if it faces the internet.
- Assume it was tried against you already: look for signs of exploitation from the date it was added, not from the day you patched.
References
H2 Security
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Start freeSource: CISA Known Exploited Vulnerabilities Catalog (public domain), catalog version 2026.10.01.