Microsoft Windows Shell Protection Mechanism Failure Vulnerability
Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security feature over a network.
What happened
Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security feature over a network.
CISA lists it as exploited, added 10 Feb 2026.
Does it affect you
Names Microsoft Windows Server. Enter the product and version you run to place it against the affected range the vendor published.
What to do
- Follow the vendor advisory for the fixed release and any interim mitigation.
msrc.microsoft.com - Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
cisa.gov
CISA’s notes for this entry:
Affected, as published to NVD
- ms-winserver
- Microsoft Windows Server: everything below 10.0.14393.8868
The record
- NVD status
- Analyzed
- Published
- 10 Feb 2026, last modified 17 Jun 2026 (NVD)
- Severity
- CVSS 3.1 base score 8.8, High — computed here from the vector; NVD states 8.8.
- Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- Weakness
- CWE-693 Protection Mechanism Failure (NVD; names by MITRE)
- Exploitation
- Listed in CISA’s Known Exploited Vulnerabilities catalogue since 10 Feb 2026; federal remediation due 03 Mar 2026. CISA entry
- Exploit probability
- EPSS 24.5%, 98th percentile — FIRST, scored 23 Oct 2026. FIRST EPSS
- Vendor
- Microsoft · Windows (CISA)
References on the NVD record
- msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21510Vendor Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21510US Government Resource
Sources
The verdict above is computed from the products and versions you entered and the affected ranges the vendor published to NVD. It does not inspect your environment, and this site never reports a product as unaffected: why.