CVE-2026-45585

Description

Microsoft is aware of a security feature bypass vulnerability in Windows publicly referred to as "YellowKey". The proof of concept for this vulnerability has been made public violating coordinated vulnerability best practices. We are issuing this CVE to provide mitigation guidance that can be implemented to protect against this vulnerability until the security update is made available.

CVSS v3.1 Score

6.8

MEDIUM

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

EPSS — Exploit Prediction

0.0011

Probability of exploitation

0.29%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-77 CWE-77

Affected Products

Vendor	Product	Versions
microsoft	windows_11_24h2	All
microsoft	windows_11_25h2	All
microsoft	windows_11_26h1	All
microsoft	windows_server_2025	All

References

Advisories & Patches

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45585

Exploits

https://github.com/Nightmare-Eclipse/YellowKey

Frequently Asked Questions

What is CVE-2026-45585? +

Microsoft is aware of a security feature bypass vulnerability in Windows publicly referred to as "YellowKey". The proof of concept for this vulnerability has been made public violating coordinated vulnerability best practices. We are issuing this CVE to provide mitigation guidance that can be implemented to protect against this vulnerability until the security update is made available. It has a CVSS v3.1 base score of 6.8 (MEDIUM).

How severe is CVE-2026-45585? +

CVE-2026-45585 has a CVSS v3.1 score of 6.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0011, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-45585? +

CVE-2026-45585 affects products from microsoft, specifically: windows_11_24h2, windows_11_25h2, windows_11_26h1, windows_server_2025. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-45585? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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