CVE-2020-16877 — Windows Elevation of Privilege Vulnerability

Executive Summary

An elevation of privilege vulnerability exists when Microsoft Windows improperly handles reparse points. An attacker who successfully exploited this vulnerability could overwrite or delete a targeted file that would normally require elevated permissions. To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability and overwrite or delete files. The security update addresses the vulnerability by correcting how Windows handles reparse points.

Overview

7.1

CVSS HIGH

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Elevation of Privilege

Released Oct 13 2020

Last Updated Oct 13 2020

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.00942 — 0.56311 percentile

CVSS Vector

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

Temporal Score: 6.4

EPSS Score

0.00942

probability of exploitation in the next 30 days

0.56311 percentile - updated 2026-06-20

View on FIRST.org

Affected Products

12 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1903 for 32-bit Systems	`4577671 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1903 for ARM64-based Systems	`4577671 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1903 for x64-based Systems	`4577671 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1909 for 32-bit Systems	`4577671 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1909 for ARM64-based Systems	`4577671 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1909 for x64-based Systems	`4577671 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 2004 for 32-bit Systems	`4579311 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 2004 for ARM64-based Systems	`4579311 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 2004 for x64-based Systems	`4579311 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server, version 1903 (Server Core installation)	`4577671 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server, version 1909 (Server Core installation)	`4577671 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server, version 2004 (Server Core installation)	`4579311 (Security Update)`	Important	Elevation of Privilege	Yes

Patches

2 patches

Article	Type	Restart
`4577671`	Security Update	Yes
`4579311`	Security Update	Yes

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

Donato Ferrante of IOActive

References

MSRC Advisory MITRE NVD