CVE-2020-0621 — Windows Security Feature Bypass Vulnerability

Executive Summary

A security feature bypass vulnerability exists in Windows 10 when third party filters are called during a password update. Successful exploitation of the vulnerability could allow a user to make use of a blocked password for their account. To exploit the vulnerability, an attacker would need have access and the current password for the target user. The update addresses how password filters are called during a password update.

Overview

4.4

CVSS MEDIUM

Important

MS Severity

Not Exploited

MS Exploit Status

N/A

MS Exploit Likelihood

Category Security Feature Bypass

Released Jan 14 2020

Last Updated Jan 14 2020

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.00972 — 0.58326 percentile

NVD CVSS 4.4 MEDIUM — matches MSRC

CVSS Vector

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

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

High

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

None

INTEGRITY

High

AVAILABILITY

None

EXPLOIT CODE MATURITY

Proof-of-Concept

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 4.0

EPSS Score

0.00972

probability of exploitation in the next 30 days

0.58326 percentile - updated 2026-07-25

View on FIRST.org

Affected Products

12 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1709 for 32-bit Systems	`4534276 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1709 for ARM64-based Systems	`4534276 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1709 for x64-based Systems	`4534276 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1803 for 32-bit Systems	`4534293 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1803 for ARM64-based Systems	`4534293 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1803 for x64-based Systems	`4534293 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1809 for 32-bit Systems	`4534273 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1809 for ARM64-based Systems	`4534273 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1809 for x64-based Systems	`4534273 (Security Update)`	Important	Security Feature Bypass	Yes
Windows Server 2019	`4534273 (Security Update)`	Important	Security Feature Bypass	Yes
Windows Server 2019 (Server Core installation)	`4534273 (Security Update)`	Important	Security Feature Bypass	Yes
Windows Server, version 1803 (Server Core Installation)	`4534293 (Security Update)`	Important	Security Feature Bypass	Yes

Patches

3 patches

Article	Type	Restart
`4534276`	Security Update	Yes
`4534293`	Security Update	Yes
`4534273`	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

Mattias Häggström, Chris Wong, and Darren Siegel of Specops Software

References

MSRC Advisory MITRE NVD