How severe is CVE-2026-21525?

CVE-2026-21525 has a CVSS score of 6.2/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-21525?

Affected package information for CVE-2026-21525 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2026-21525?

No fixed version has been published for CVE-2026-21525 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2026-21525 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-21525 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-21525?

CVE-2026-21525 has an EPSS (Exploit Prediction Scoring System) score of 9.4%, placing it in the 93th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

Is CVE-2026-21525 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2026-21525 (Microsoft Windows NULL Pointer Dereference Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-02-10. CISA required all US federal civilian agencies to remediate this vulnerability by 2026-03-03. The required action was: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2026-21525?

CVE-2026-21525 is classified as NULL Pointer Dereference (CWE-476). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2026-21525?

CVE-2026-21525 affects microsoft windows 10 21h2; microsoft windows 10 22h2; microsoft windows 10 1607; microsoft windows 10 1809, and 9 more product(s). Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2026-21525 published, and has it been updated?

CVE-2026-21525 was published on February 10, 2026 and was last updated on March 30, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2026-02-10 — agencies required to remediate by 2026-03-03

CVE-2026-21525

MEDIUM

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

Published

Feb 10, 2026

Updated

Mar 30, 2026

Affected

0 pkgs

Patched

None yet

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

9.4%probability of exploitation in next 30 days

Lower Risk93th percentile+0.53%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

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

Affected Products

13 products · 23 configurations

windows 10 21h2microsoft

< 10.0.19044.6937

range

windows 10 22h2microsoft

< 10.0.19045.6937

range

windows 10 1607microsoft

< 10.0.14393.8868

range

windows 10 1809microsoft

< 10.0.17763.8389

range

windows 11 23h2microsoft

< 10.0.22631.6649

range

windows 11 24h2microsoft

< 10.0.26100.7781

range

Frequently Asked Questions

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

O3 Security · Impact-Aware SCA

Is CVE-2026-21525 in your stack?

O3 detects CVE-2026-21525 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my stack How O3 SCA works