CVE-2020-1277 — Windows Installer Elevation of Privilege Vulnerability

Executive Summary

An elevation of privilege vulnerability exists in Windows Installer because of the way Windows Installer handles certain filesystem operations. To exploit the vulnerability, an attacker would require unprivileged execution on the victim system. After successfully exploiting the vulnerability, an attacker could run arbitrary code with elevated privileges. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. The security update addresses the vulnerability by correcting the way Windows Installer handles certain filesystem operations.

Overview

7.8

CVSS HIGH

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Elevation of Privilege

Released Jun 9 2020

Last Updated Jun 9 2020

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.00703 — 0.48372 percentile

NVD CVSS 7.8 HIGH — matches MSRC

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

High

INTEGRITY

High

AVAILABILITY

High

EXPLOIT CODE MATURITY

Proof-of-Concept

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 7.0

EPSS Score

0.00703

probability of exploitation in the next 30 days

0.48372 percentile - updated 2026-06-21

View on FIRST.org

Affected Products

17 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1809 for 32-bit Systems	`4561608 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1809 for ARM64-based Systems	`4561608 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1809 for x64-based Systems	`4561608 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1903 for 32-bit Systems	`4560960 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1903 for ARM64-based Systems	`4560960 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1903 for x64-based Systems	`4560960 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1909 for 32-bit Systems	`4560960 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1909 for ARM64-based Systems	`4560960 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 1909 for x64-based Systems	`4560960 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 2004 for 32-bit Systems	`4557957 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 2004 for ARM64-based Systems	`4557957 (Security Update)`	Important	Elevation of Privilege	Yes
Windows 10 Version 2004 for x64-based Systems	`4557957 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2019	`4561608 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server 2019 (Server Core installation)	`4561608 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server, version 1903 (Server Core installation)	`4560960 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server, version 1909 (Server Core installation)	`4560960 (Security Update)`	Important	Elevation of Privilege	Yes
Windows Server, version 2004 (Server Core installation)	`4557957 (Security Update)`	Important	Elevation of Privilege	Yes

Patches

3 patches

Article	Type	Restart
`4561608`	Security Update	Yes
`4560960`	Security Update	Yes
`4557957`	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

360 BugCloud, Zhiniang Peng (@edwardzpeng) of Qihoo 360 Core security and Haoran Qin (@Q4n)

References

MSRC Advisory MITRE NVD