Feb 2026: Windows Remote Access Connection Manager Denial of Service Vulnerability
CVE-2026-21525 Published on February 10, 2026

Windows Remote Access Connection Manager Denial of Service Vulnerability
Null pointer dereference in Windows Remote Access Connection Manager allows an unauthorized attacker to deny service locally.

Vendor Advisory NVD

Known Exploited Vulnerability

This Microsoft Windows NULL Pointer Dereference Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. Microsoft Windows Remote Access Connection Manager contains a NULL pointer dereference that could allow an unauthorized attacker to deny service locally.

The following remediation steps are recommended / required by March 3, 2026: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Weakness Type

NULL Pointer Dereference

A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions.

Products Associated with CVE-2026-21525

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2026-21525 are published in these products:

Microsoft Windows 10

Microsoft Windows Server 2019

Microsoft Windows Server 2022

Microsoft Windows Server 2025

Microsoft Windows 11 25h2

Microsoft Windows 11 23h2

Microsoft Windows Server 23h2

Microsoft Windows 11 24h2

Microsoft Windows Server 2016

Microsoft Windows Server 2012

Microsoft Windows Server 2012 R2

Microsoft Windows 11 26h1

Affected Versions

Microsoft Windows 10 Version 1607:

Version 10.0.14393.0 and below 10.0.14393.8868 is affected.

Microsoft Windows 10 Version 1809:

Version 10.0.17763.0 and below 10.0.17763.8389 is affected.

Microsoft Windows 10 Version 21H2:

Version 10.0.19044.0 and below 10.0.19044.6937 is affected.

Microsoft Windows 10 Version 22H2:

Version 10.0.19045.0 and below 10.0.19045.6937 is affected.

Microsoft Windows 11 version 22H3:

Version 10.0.22631.0 and below 10.0.22631.6649 is affected.

Microsoft Windows 11 Version 23H2:

Version 10.0.22631.0 and below 10.0.22631.6649 is affected.

Microsoft Windows 11 Version 24H2:

Version 10.0.26100.0 and below 10.0.26100.7840 is affected.

Microsoft Windows 11 Version 25H2:

Version 10.0.26200.0 and below 10.0.26200.7840 is affected.

Microsoft Windows 11 version 26H1:

Version 10.0.28000.0 and below 10.0.28000.1575 is affected.

Microsoft Windows 11 Version 26H1:

Version 10.0.28000.0 and below 10.0.28000.1575 is affected.

Microsoft Windows Server 2012:

Version 6.2.9200.0 and below 6.2.9200.25923 is affected.

Microsoft Windows Server 2012 (Server Core installation):

Version 6.2.9200.0 and below 6.2.9200.25923 is affected.

Microsoft Windows Server 2012 R2:

Version 6.3.9600.0 and below 6.3.9600.23022 is affected.

Microsoft Windows Server 2012 R2 (Server Core installation):

Version 6.3.9600.0 and below 6.3.9600.23022 is affected.

Microsoft Windows Server 2016:

Version 10.0.14393.0 and below 10.0.14393.8868 is affected.

Microsoft Windows Server 2016 (Server Core installation):

Version 10.0.14393.0 and below 10.0.14393.8868 is affected.

Microsoft Windows Server 2019:

Version 10.0.17763.0 and below 10.0.17763.8389 is affected.

Microsoft Windows Server 2019 (Server Core installation):

Version 10.0.17763.0 and below 10.0.17763.8389 is affected.

Microsoft Windows Server 2022:

Version 10.0.20348.0 and below 10.0.20348.4773 is affected.

Microsoft Windows Server 2022, 23H2 Edition (Server Core installation):

Version 10.0.25398.0 and below 10.0.25398.2149 is affected.

Microsoft Windows Server 2025:

Version 10.0.26100.0 and below 10.0.26100.32370 is affected.

Microsoft Windows Server 2025 (Server Core installation):

Version 10.0.26100.0 and below 10.0.26100.32370 is affected.

Exploit Probability

EPSS

2.16%

Percentile

83.98%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.