CVE-2021-31956

HIGH KEV

Windows NTFS - Elevation of Privilege via Integer Underflow

Title source: llm
STIX 2.1

Exploitation Summary

CVE-2021-31956 is actively exploited and listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added November 3, 2021. EIP tracks 5 public exploits from researchers including Y3A, hoangprod, deletehead.

AI-analyzed exploit summary This repository contains a functional exploit for CVE-2021-31956, a Windows kernel vulnerability involving heap overflow in the Windows Notification Facility (WNF). The exploit demonstrates local privilege escalation by manipulating WNF state data to achieve arbitrary write primitives and token theft.

Description

Windows NTFS Elevation of Privilege Vulnerability

Exploits (5)

nomisec WORKING POC 5 stars
by Y3A · local
https://github.com/Y3A/CVE-2021-31956

This repository contains a functional exploit for CVE-2021-31956, a Windows kernel vulnerability involving heap overflow in the Windows Notification Facility (WNF). The exploit demonstrates local privilege escalation by manipulating WNF state data to achieve arbitrary write primitives and token theft.

Classification
Working Poc 95%
Attack Type
Lpe
Complexity
Complex
Reliability
Reliable
Target: Microsoft Windows (kernel)
No auth needed
Prerequisites: Local access to a vulnerable Windows system · Kernel-level heap manipulation capabilities
devstral-2 · analyzed Feb 18, 2026 Full analysis →
nomisec WORKING POC 4 stars
by hoangprod · local
https://github.com/hoangprod/CVE-2021-31956-POC

This repository contains a functional proof-of-concept exploit for CVE-2021-31956, leveraging a heap overflow in Windows NTFS Extended Attributes (EA) to corrupt adjacent pool objects, specifically targeting _WNF_STATE_DATA structures. The exploit demonstrates memory corruption techniques to achieve local privilege escalation (LPE) by manipulating undocumented NT API calls.

Classification
Working Poc 95%
Attack Type
Lpe
Complexity
Complex
Reliability
Racy
Target: Microsoft Windows (NTFS driver, specifically affecting Windows 10 and likely other versions)
No auth needed
Prerequisites: Local access to the target system · Ability to create and manipulate files on an NTFS volume
devstral-2 · analyzed Feb 18, 2026 Full analysis →
nomisec STUB
by deletehead · poc
https://github.com/deletehead/Pool-Overflow-CVE-2021-31956

The repository contains only a placeholder README and a single empty C++ file, with no functional exploit code or technical details about CVE-2021-31956.

Classification
Stub 90%
Attack Type
Other
Complexity
Trivial
Reliability
Theoretical
Target: unknown
No auth needed
devstral-2 · analyzed Feb 18, 2026 Full analysis →
nomisec WORKING POC
by hzshang · poc
https://github.com/hzshang/CVE-2021-31956

This repository contains a functional exploit for CVE-2021-31956, a Windows NTFS vulnerability involving out-of-bounds (OOB) write via Extended Attributes (EA) manipulation. The exploit leverages WNF (Windows Notification Facility) state data corruption to achieve arbitrary read/write primitives.

Classification
Working Poc 95%
Attack Type
Lpe
Complexity
Complex
Reliability
Racy
Target: Microsoft Windows NTFS (Windows 10, Windows Server 2019)
No auth needed
Prerequisites: Local access to the target system · Ability to create files in a writable directory
devstral-2 · analyzed Feb 18, 2026 Full analysis →
patchapalooza WORKING POC
by aazhuliang · local
https://github.com/aazhuliang/CVE-2021-31956-EXP

This repository contains a functional exploit for CVE-2021-31956, a Windows kernel vulnerability involving WNF (Windows Notification Facility) state name manipulation and EA (Extended Attributes) file operations. The exploit demonstrates memory corruption via heap spraying and arbitrary kernel memory read/write primitives.

Classification
Working Poc 95%
Attack Type
Lpe
Complexity
Complex
Reliability
Reliable
Target: Microsoft Windows (kernel)
No auth needed
Prerequisites: Windows system with vulnerable kernel · ability to execute arbitrary code
devstral-2 · analyzed Feb 23, 2026 Full analysis →

Scores

CVSS v3 7.8
EPSS 0.9072
EPSS Percentile 99.6%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment
Exploitation active
Automatable no
Technical Impact total

Details

CISA KEV 2021-11-03
VulnCheck KEV 2021-04-14
InTheWild.io 2021-04-14
ENISA EUVD EUVD-2021-18829
CWE
CWE-191
Status published
Products (18)
microsoft/windows_10_1507 < 10.0.10240.18967
microsoft/windows_10_1607 < 10.0.14393.4467
microsoft/windows_10_1809 < 10.0.17763.1999
microsoft/windows_10_1909 < 10.0.18363.1621
microsoft/windows_10_2004 < 10.0.19041.1052
microsoft/windows_10_20h2 < 10.0.19042.1052
microsoft/windows_10_21h1 < 10.0.19043.1052
microsoft/windows_7
microsoft/windows_8.1
microsoft/windows_rt_8.1
... and 8 more
Published Jun 08, 2021
KEV Added Nov 03, 2021
Tracked Since Feb 18, 2026