CVE-2026-21510

Microsoft Windows Shell Protection Mechanism Failure Vulnerability

Microsoft — Windows

Added to KEV catalog: 10 February 2026
Federal remediation due date: 3 March 2026
Weakness classification (CWE): CWE-693

CISA Description

Microsoft Windows Shell contains a protection mechanism failure vulnerability that could allow an unauthorized attacker to bypass a security feature over a network.

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.

Notes

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21510 ; https://nvd.nist.gov/vuln/detail/CVE-2026-21510

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