CVE-2019-0637 — Windows Defender Firewall Security Feature Bypass Vulnerability

Executive Summary

A security feature bypass vulnerability exists when Windows Defender Firewall incorrectly applies firewall profiles to cellular network connections. This vulnerability occurs when Windows is connected to both an ethernet network and a cellular network. An attacker would have no way to trigger this vulnerability remotely, and this vulnerability by itself does not allow Windows to be exploited. This update addresses the behavior by correcting how Windows Defender Firewall handles firewall profiles when ethernet and cellular network connections are both present.

Overview

7.5

CVSS HIGH

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Security Feature Bypass

Released Feb 12 2019

Last Updated Feb 12 2019

Publicly Disclosed Yes

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.04297 — 0.90108 percentile

NVD CVSS 7.5 HIGH — differs from MSRC

CVSS Vector

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N/E:P/RL:O/RC:C

ATTACK VECTOR

Network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

None

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

None

INTEGRITY

Low

AVAILABILITY

None

EXPLOIT CODE MATURITY

Proof-of-Concept

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 4.8

EPSS Score

0.04297

probability of exploitation in the next 30 days

0.90108 percentile - updated 2026-07-25

View on FIRST.org

Affected Products

13 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1709 for 32-bit Systems	`4486996 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1709 for ARM64-based Systems	`4486996 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1709 for x64-based Systems	`4486996 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1803 for 32-bit Systems	`4487017 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1803 for ARM64-based Systems	`4487017 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1803 for x64-based Systems	`4487017 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1809 for 32-bit Systems	`4487044 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1809 for ARM64-based Systems	`4487044 (Security Update)`	Important	Security Feature Bypass	Yes
Windows 10 Version 1809 for x64-based Systems	`4487044 (Security Update)`	Important	Security Feature Bypass	Yes
Windows Server 2019	`4487044 (Security Update)`	Important	Security Feature Bypass	Yes
Windows Server 2019 (Server Core installation)	`4487044 (Security Update)`	Important	Security Feature Bypass	Yes
Windows Server, version 1709 (Server Core Installation)	`4486996 (Security Update)`	Important	Security Feature Bypass	Yes
Windows Server, version 1803 (Server Core Installation)	`4487017 (Security Update)`	Important	Security Feature Bypass	Yes

Patches

3 patches

Article	Type	Restart
`4486996`	Security Update	Yes
`4487017`	Security Update	Yes
`4487044`	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

None

References

MSRC Advisory MITRE NVD