Microsoft Windows Shell Protection Mechanism Failure Vulnerability (CVE-2026-21510)
Severity: high · Patch status: unknown · Since 2026-02-10 · CVE-2026-21510
Microsoft Windows Shell contains a protection mechanism failure vulnerability that could allow an unauthorized attacker to bypass a security feature over a network. CISA added CVE-2026-21510 to its Known Exploited Vulnerabilities catalog on Feb 10, 2026, which means attackers are exploiting it in the wild.
What to do
- Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- US federal agencies must remediate by Mar 3, 2026 (BOD 22-01); treat that as the outer limit.
Sources
All live incidents on Threat Watch
