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CVE-2026-21510: Microsoft Windows Shell Protection Mechanism Failure Vulnerability

criticalknown exploitedCVE-2026-21510
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
Microsoft Windows Shell contains a protection mechanism failure vulnerability that could allow an unauthorized attacker to bypass a security feature over a network.

CSIRTS triage

vendor: Microsoftproduct: Windows ShellAuthentication bypass
What
Windows Shell contains a protection mechanism failure vulnerability.
Who is affected
Users of Microsoft Windows Shell.
Urgency
Remediation is urgent due to active exploitation and critical severity.
Action
Apply the latest security updates for Microsoft Windows.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source
CISA Known Exploited Vulnerabilities (US · database · site)
Severity
critical
Published
2026-02-10
Exploitation
Observed in the wild (CISA KEV)

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-21510

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2026-21510coverage & exploitation statusNVD · CVE.org

Recent advisories for Microsoft Windows Shell

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

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