Actively exploited
Listed in CISA’s Known Exploited Vulnerabilities catalog since November 17, 2021.
CVE-2021-40449
Microsoft Windows Win32k Privilege Escalation Vulnerability
Added to KEV November 17, 2021
Alert details
- Source feed
- CISA KEV
- CVE ID
- CVE-2021-40449
- CWE
- CWE-416
- Affected products
- Windows · Microsoft Windows · Microsoft
What happened
Unspecified vulnerability allows for an authenticated user to escalate privileges.
What it means for your business
Microsoft Windows is listed in CISA's Known Exploited Vulnerabilities catalog (CVE-2021-40449). Unspecified vulnerability allows for an authenticated user to escalate privileges. CISA remediation due date: 2021-12-01. If you need help checking exposure, call (864) 335-9223.
Required action
Apply updates per vendor instructions.
CISA due date: December 1, 2021
Sources
Related briefs
Microsoft Windows Heap-Based Buffer Overflow Vulnerability
Microsoft Windows is listed in CISA's Known Exploited Vulnerabilities catalog (CVE-2026-85880). Microsoft Windows Advanced Local Procedure Call contains a heap-based buffer overflow vulnerability that allows an attacker to elevate privileges locally. CISA remediation due date: 2026-09-22. If you need help checking exposure, call (864) 335-9223.
Heap buffer overflow in ANGLE in Microsoft Edge vulnerability
Heap buffer overflow in ANGLE in Microsoft Edge vulnerability (CVE-2025-10502) was added to Microsoft’s security update guidance. Information published. If you need help checking exposure, call (864) 335-9223.
Microsoft Exchange Server Elevation of Privilege vulnerability
Microsoft Exchange Server Elevation of Privilege vulnerability (CVE-2026-96940) was added to Microsoft’s security update guidance. Weak authorization in Microsoft Exchange Server allows an authenticated attacker to elevate privileges over a network. If you need help checking exposure, call (864) 335-9223.
Windows Web Proxy Auto-Discovery Protocol (WPAD) Elevation of Privilege vulnerability
Windows Web Proxy Auto-Discovery Protocol (WPAD) Elevation of Privilege vulnerability (CVE-2026-49800) was added to Microsoft’s security update guidance. Updated an acknowledgement. This is an informational change only. If you need help checking exposure, call (864) 335-9223.
Need help patching?
PremierePC monitors KEV alerts for managed clients and helps teams prioritize remediation before attackers do.