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Advisory severityMedium6.2Microsoft Server Exploited CISA KEV

Medium [CVE-2026-21525] Windows Remote Access Connection Manager Denial of Service Vulnerability

This medium-severity Microsoft Server advisory covers CVE-2026-21525 affecting Windows Server 2012 (Server Core installation), Windows Server 2012 R2 (Server Core installation), Windows Server 2016 (Server Core installation).

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-21525 Source published Source updated

VulniPulse record published

CVE-2026-21525
Affected products & platforms
Microsoft ServerWindows Server
Open source advisory

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Summary

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

Affected products named by the advisory: Windows Server 2012; Windows Server 2012 (Server Core installation); Windows Server 2012 R2; Windows Server 2012 R2 (Server Core installation); and 8 more.

Affected products named by the advisory: Windows Server 2016 (Server Core installation); Windows Server 2019 (Server Core installation); Windows Server 2022, 23H2 Edition (Server Core installation); Windows Server 2025 (Server Core installation).

CISA Known Exploited Vulnerability

Listed:
Feb 10, 2026 · federal remediation due Mar 3, 2026
Required action:
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Ransomware use:
Unknown

KEV is a prioritization signal from CISA — remediation detail still comes from the vendor advisory.

Affected versions
  • Windows 10 Version 1607 10.0.14393.0 before 10.0.14393.8868
  • Windows 10 Version 1809 10.0.17763.0 before 10.0.17763.8389
  • Windows 10 Version 21H2 10.0.19044.0 before 10.0.19044.6937
  • Windows 10 Version 22H2 10.0.19045.0 before 10.0.19045.6937
  • Windows 11 version 22H3 10.0.22631.0 before 10.0.22631.6649
  • Windows 11 Version 23H2 10.0.22631.0 before 10.0.22631.6649
  • Windows 11 Version 24H2 10.0.26100.0 before 10.0.26100.7840
  • Windows 11 Version 25H2 10.0.26200.0 before 10.0.26200.7840
  • Windows 11 version 26H1 10.0.28000.0 before 10.0.28000.1575
  • Windows 11 Version 26H1 10.0.28000.0 before 10.0.28000.1575
  • Windows Server 2012 6.2.9200.0 before 6.2.9200.25923
  • Windows Server 2012 (Server Core installation) 6.2.9200.0 before 6.2.9200.25923

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Fixed versions
  • 10.0.14393.8868
  • 10.0.17763.8389
  • 10.0.19044.6937
  • 10.0.19045.6937
  • 10.0.22631.6649
  • 10.0.26100.7840
  • 10.0.26200.7840
  • 10.0.28000.1575
  • 6.2.9200.25923
  • 6.3.9600.23022
  • 10.0.20348.4773
  • 10.0.25398.2149

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Mitigation

Upgrade to a fixed release: 10.0.14393.8868, 10.0.17763.8389, 10.0.19044.6937, 10.0.19045.6937, 10.0.22631.6649, 10.0.26100.7840. That is the remediation for this advisory.

The vendor advisory may list additional interim mitigations or workarounds not captured here — review it before change work.

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Discussion(0)

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