CVE-2020-1391 — Windows Agent Activation Runtime Information Disclosure Vulnerability

Executive Summary

An information disclosure vulnerability exists when the Windows Agent Activation Runtime (AarSvc) fails to properly handle objects in memory. An attacker who successfully exploited the vulnerability could obtain information to further compromise the user’s system. To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application. The update addresses the vulnerability by correcting how the Windows Agent Activation Runtime handles objects in memory.

Overview

5.5

CVSS MEDIUM

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Information Disclosure

Released Jul 14 2020

Last Updated Jul 14 2020

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.01224 — 0.64869 percentile

NVD CVSS 5.5 MEDIUM — matches MSRC

CVSS Vector

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

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

High

INTEGRITY

None

AVAILABILITY

None

EXPLOIT CODE MATURITY

Proof-of-Concept

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 5.0

EPSS Score

0.01224

probability of exploitation in the next 30 days

0.64869 percentile - updated 2026-06-21

View on FIRST.org

Affected Products

12 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1903 for 32-bit Systems	`4565483 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1903 for ARM64-based Systems	`4565483 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1903 for x64-based Systems	`4565483 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1909 for 32-bit Systems	`4565483 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1909 for ARM64-based Systems	`4565483 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1909 for x64-based Systems	`4565483 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 2004 for 32-bit Systems	`4565503 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 2004 for ARM64-based Systems	`4565503 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 2004 for x64-based Systems	`4565503 (Security Update)`	Important	Information Disclosure	Yes
Windows Server, version 1903 (Server Core installation)	`4565483 (Security Update)`	Important	Information Disclosure	Yes
Windows Server, version 1909 (Server Core installation)	`4565483 (Security Update)`	Important	Information Disclosure	Yes
Windows Server, version 2004 (Server Core installation)	`4565503 (Security Update)`	Important	Information Disclosure	Yes

Patches

2 patches

Article	Type	Restart
`4565483`	Security Update	Yes
`4565503`	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

Anonymous researcher

References

MSRC Advisory MITRE NVD