CVE-2021-31956

Windows NTFS Elevation of Privilege Vulnerability

Exploited in attacks High 7.8 Attack chance: 22%

What it is

Windows NTFS Elevation of Privilege Vulnerability

CISA: Microsoft Windows New Technology File System (NTFS) contains an unspecified vulnerability that allows attackers to escalate privileges via a specially crafted application.

What to do

Apply updates per vendor instructions.

Deadline for US federal agencies: November 17, 2021

Added to the CISA list: November 3, 2021
Published: June 8, 2021
Severity: High 7.8 CVSS 3.1
Chance of attacks in the next 30 days (EPSS): 22% in the top 2.3% of all known vulnerabilities
Weakness: CWE-191 CWE-787
More details: NVD · CVE.org · CISA

All references (1)

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31956

More exploited flaws from Microsoft

Added	Vulnerability	Product	Severity	Attack chance
Oct 13, 2026	Command InjectionCVE-2026-96951	Windows	High 8.8	9.8%
Sep 8, 2026	Link FollowingCVE-2026-81963	Windows	High 7.8	0.4%
Sep 8, 2026	Heap-Based Buffer OverflowCVE-2026-85880	Windows	High 7.8	0.4%
May 20, 2026	Buffer OverflowCVE-2008-4250	Windows	Critical 9.8	99%
Apr 28, 2026	Protection Mechanism FailureCVE-2026-32202	Windows	Medium 4.3	71%
Apr 13, 2026	Out-of-Bounds ReadCVE-2023-36424	Windows	High 7.8	12%
Apr 13, 2026	Link FollowingCVE-2025-60710used by ransomware	Windows	High 7.8	4.6%
Feb 17, 2026	Microsoft Windows Video ActiveX Control Remote Code ExecutionCVE-2008-0015	Windows	High 8.8	77%

All of them →

Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.