What is CVE-2026-21525?

CVE-2026-21525 is a medium-severity vulnerability in Microsoft Windows 10 Version 1607, classified under NULL Pointer Dereference. CVSS score: 6.2/10. Published 2026-02-10.

How severe is CVE-2026-21525?

Medium severity. CVSS v3 base score is 6.2 out of 10.

Is CVE-2026-21525 known to be exploited?

Yes. CVE-2026-21525 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-02-10), indicating it is being actively exploited.

NULL pointer dereference in Microsoft Windows 10 Version 1607

CVE-2026-21525

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

EPSS: 0.094 (92.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.2 (Medium). Vector: 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.

Affected products

Microsoft Windows 10 Version 1607 — versions 10.0.14393.0
Microsoft Windows 10 Version 1809 — versions 10.0.17763.0
Microsoft Windows 10 Version 21h2 — versions 10.0.19044.0
Microsoft Windows 10 Version 22h2 — versions 10.0.19045.0
Microsoft Windows 11 Version 22h3 — versions 10.0.22631.0
Microsoft Windows 11 Version 23h2 — versions 10.0.22631.0
Microsoft Windows 11 Version 24h2 — versions 10.0.26100.0
Microsoft Windows 11 Version 25h2 — versions 10.0.26200.0
Microsoft Windows 11 Version 26h1 — versions 10.0.28000.0
Microsoft Windows Server 2012 — versions 6.2.9200.0

Weakness classification (CWE)

CWE-476 — NULL Pointer Dereference

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2026-02-10. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2026-03-03.

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.

References

Windows Remote Access Connection Manager Denial of Service Vulnerability (vendor-advisory, patch)

Frequently asked questions

What is CVE-2026-21525?: CVE-2026-21525 is a medium-severity vulnerability in Microsoft Windows 10 Version 1607, classified under NULL Pointer Dereference. CVSS score: 6.2/10. Published 2026-02-10.
How severe is CVE-2026-21525?: Medium severity. CVSS v3 base score is 6.2 out of 10.
Is CVE-2026-21525 known to be exploited?: Yes. CVE-2026-21525 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-02-10), indicating it is being actively exploited.