Skip to content
Noroxi
NVD / CVE Program· CNA microsoft

CVE-2026-21525: Windows Remote Access Connection Manager Denial of Service Vulnerability

MediumCVSS 6.2 · v3.1KEVWeaponized Fix available

Noroxi assessment

Priority: Plan (action score 56/100)

  • CISA has confirmed exploitation in the wild (Feb 10, 2026). Remediation deadline for US federal agencies: Mar 3, 2026.
  • Probability of exploitation in the next 30 days: 5% (FIRST EPSS); higher than 92.4% of all records.
  • Someone with local access to the system can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Windows 10 Version 1607 for 32-bit Systems 10.0.14393.8868; Windows 10 Version 1607 for x64-based Systems 10.0.14393.8868; Windows 10 Version 1809 for 32-bit Systems 10.0.17763.8389.

Add it to your regular patch cycle. Upgrade to Windows 10 Version 1607 for 32-bit Systems 10.0.14393.8868; Windows 10 Version 1607 for x64-based Systems 10.0.14393.8868; Windows 10 Version 1809 for 32-bit Systems 10.0.17763.8389 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · CISA KEV · FIRST EPSS

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

Published
Feb 10, 2026
Updated
Aug 19, 2026
EPSS
5.0% · 92th percentile

Report tools

JSON

Action score

56

Plan

Add it to your regular patch cycle.

CVSS
24 / 40 · 6.2 / 10
CISA KEV
30 / 30 · Listed
EPSS
2 / 30 · 5.0%

CISA SSVC decision

Exploitation
active
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · microsoft
6.2
NVD has not scored this yet; the score shown is the CNA’s.

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Actively exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on Feb 10, 2026. That signals real attacks, not theory.

Remediation deadline for US federal agencies: Mar 3, 2026.

Get told when this record changes

  • In CISA KEV: exploitation in the wild confirmed
  • Weaponized exploit exists
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-21525

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits every 10 minutes on paid plans, on the hour on the free plan.

Your free account also gets you

  • CVE alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools, at most 30 a day (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for microsoft records
Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
microsoftwindows 10 1607
microsoftwindows 10 1809
microsoftwindows 10 21h2
microsoftwindows 10 22h2
microsoftwindows 11 23h2
microsoftwindows 11 24h2
microsoftwindows 11 25h2
microsoftwindows server 2012
microsoftwindows server 2016
microsoftwindows server 2019
microsoftwindows server 2022
microsoftwindows server 2022 23h2

and 1 more

Versions reported by the vendor

Affected version ranges reported by the assigning authority (microsoft). Independent of NVD's CPE analysis and usually ahead of it.

  • Microsoft Windows 10 Version 1607

    • 10.0.14393.0 and later · before 10.0.14393.8868affected

  • Microsoft Windows 10 Version 1809

    • 10.0.17763.0 and later · before 10.0.17763.8389affected

  • Microsoft Windows 10 Version 21H2

    • 10.0.19044.0 and later · before 10.0.19044.6937affected

  • Microsoft Windows 10 Version 22H2

    • 10.0.19045.0 and later · before 10.0.19045.6937affected

  • Microsoft Windows 11 version 22H3

    • 10.0.22631.0 and later · before 10.0.22631.6649affected

  • Microsoft Windows 11 Version 23H2

    • 10.0.22631.0 and later · before 10.0.22631.6649affected

  • Microsoft Windows 11 Version 24H2

    • 10.0.26100.0 and later · before 10.0.26100.7840affected

  • Microsoft Windows 11 Version 25H2

    • 10.0.26200.0 and later · before 10.0.26200.7840affected

  • Microsoft Windows 11 version 26H1

    • 10.0.28000.0 and later · before 10.0.28000.1575affected

  • Microsoft Windows 11 Version 26H1

    • 10.0.28000.0 and later · before 10.0.28000.1575affected

  • Microsoft Windows Server 2012

    • 6.2.9200.0 and later · before 6.2.9200.25923affected

  • Microsoft Windows Server 2012 (Server Core installation)

    • 6.2.9200.0 and later · before 6.2.9200.25923affected
Affected versions · NVD (7)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • microsoft windows server 2012all versions
  • microsoft windows server 2012r2
  • microsoft windows server 2016before 10.0.14393.8868
  • microsoft windows server 2019before 10.0.17763.8389
  • microsoft windows server 2022before 10.0.20348.4711
  • microsoft windows server 2022 23h2before 10.0.25398.2149
  • microsoft windows server 2025before 10.0.26100.32313

Same product

microsoft: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-33824Windows Internet Key Exchange (IKE) Service Extensions Remote Code Execution VulnerabilityKEV
    92Now
  • CVE-2018-8174A remote code execution vulnerability exists in the way that the VBScript engine handles objects in memory, aka "Windows VBScript Engine…KEV
    86Now
  • CVE-2026-21510Windows Shell Security Feature Bypass VulnerabilityKEV
    83Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-21513Feb 10, 2026 · MSHTML Framework Security Feature Bypass VulnerabilityKEV
    70This week
  • ← EarlierCVE-2026-21519Feb 10, 2026 · Desktop Window Manager Elevation of Privilege VulnerabilityKEV
    62This week
  • Later →CVE-2026-21533Feb 10, 2026 · Windows Remote Desktop Services Elevation of Privilege VulnerabilityKEV
    62This week

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Windows 10 Version 1607 for 32-bit Systems10.0.14393.8868 · KB5075999Microsoft (MSRC)
Windows 10 Version 1607 for x64-based Systems10.0.14393.8868 · KB5075999Microsoft (MSRC)
Windows 10 Version 1809 for 32-bit Systems10.0.17763.8389 · KB5075904Microsoft (MSRC)
Windows 10 Version 1809 for x64-based Systems10.0.17763.8389 · KB5075904Microsoft (MSRC)
Windows 10 Version 21H2 for 32-bit Systems10.0.19044.6937 · KB5075912Microsoft (MSRC)
Windows 10 Version 21H2 for ARM64-based Systems10.0.19044.6937 · KB5075912Microsoft (MSRC)
Windows 10 Version 21H2 for x64-based Systems10.0.19044.6937 · KB5075912Microsoft (MSRC)
Windows 10 Version 22H2 for 32-bit Systems10.0.19045.6937 · KB5075912Microsoft (MSRC)
Windows 10 Version 22H2 for ARM64-based Systems10.0.19045.6937 · KB5075912Microsoft (MSRC)
Windows 10 Version 22H2 for x64-based Systems10.0.19045.6937 · KB5075912Microsoft (MSRC)
Windows 11 Version 23H2 for ARM64-based Systems10.0.22631.6649 · KB5075941Microsoft (MSRC)
Windows 11 Version 23H2 for x64-based Systems10.0.22631.6649 · KB5075941Microsoft (MSRC)
Windows 11 Version 24H2 for ARM64-based Systems10.0.26100.7781 · KB5077212Microsoft (MSRC)
Windows 11 Version 24H2 for ARM64-based Systems10.0.26100.7840 · KB5077181Microsoft (MSRC)
Windows 11 Version 24H2 for x64-based Systems10.0.26100.7781 · KB5077212Microsoft (MSRC)
Windows 11 Version 24H2 for x64-based Systems10.0.26100.7840 · KB5077181Microsoft (MSRC)
Windows 11 Version 25H2 for ARM64-based Systems10.0.26200.7781 · KB5077212Microsoft (MSRC)
Windows 11 Version 25H2 for ARM64-based Systems10.0.26200.7840 · KB5077181Microsoft (MSRC)
Windows 11 Version 25H2 for x64-based Systems10.0.26200.7781 · KB5077212Microsoft (MSRC)
Windows 11 Version 25H2 for x64-based Systems10.0.26200.7840 · KB5077181Microsoft (MSRC)
Windows 11 Version 26H1 for ARM64-based Systems10.0.28000.1575 · KB5077179Microsoft (MSRC)
Windows 11 version 26H1 for x64-based Systems10.0.28000.1575 · KB5077179Microsoft (MSRC)
Windows Server 20126.2.9200.25923 · KB5075971Microsoft (MSRC)
Windows Server 2012 (Server Core installation)6.2.9200.25923 · KB5075971Microsoft (MSRC)
Windows Server 2012 R26.3.9600.23022 · KB5075970Microsoft (MSRC)
Windows Server 2012 R2 (Server Core installation)6.3.9600.23022 · KB5075970Microsoft (MSRC)
Windows Server 201610.0.14393.8868 · KB5075999Microsoft (MSRC)
Windows Server 2016 (Server Core installation)10.0.14393.8868 · KB5075999Microsoft (MSRC)
Windows Server 201910.0.17763.8389 · KB5075904Microsoft (MSRC)
Windows Server 2019 (Server Core installation)10.0.17763.8389 · KB5075904Microsoft (MSRC)

+9

Exploit status

Weaponized

A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. CISA KEV-1 d
  2. Published
  3. TodayNov 14, 2026+276 d

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-2516528 days apartPerformance Counters for Windows Elevation of Privilege Vulnerability
    31Monitor
  • CVE-2025-6246663 days apartWindows Client-Side Caching Elevation of Privilege Vulnerability
    31Monitor
  • CVE-2026-77489210 days apartWindows Biometric Service Elevation of Privilege Vulnerability
    31Monitor
  • CVE-2026-70566245 days apartWindows Schannel Elevation of Privilege Vulnerability
    31Monitor
  • CVE-2026-96953245 days apartWindows Universal Disk Format File System Driver (UDFS) Remote Code Execution Vulnerability
    31Monitor
  • CVE-2024-38233518 days apartWindows Networking Denial of Service Vulnerability
    31Monitor

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · public bounty program.

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records