How to fix CVE-2026-96951: Microsoft Windows (exploited in the wild)

Improper neutralization of special elements used in a command ('command injection') in Windows Shell allows an unauthorized attacker to bypass a security feature over a network.

• Severity: HIGH (CVSS 3.1 8.8, vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).
• Weakness: CWE-77.
• NVD published 2026-10-13, status Analyzed.

Anyone running Microsoft Windows in the version ranges below. Internet-facing instances are the priority.

• microsoft windows 10 1607: up to (not including) 10.0.14393.9612.
• microsoft windows 10 1809: up to (not including) 10.0.17763.9376.
• microsoft windows 10 21h2: up to (not including) 10.0.19044.7807.
• microsoft windows 10 22h2: up to (not including) 10.0.19045.7807.
• microsoft windows 11 23h2: up to (not including) 10.0.22631.7652.
• microsoft windows 11 24h2: up to (not including) 10.0.26100.9711.
• microsoft windows 11 25h2: up to (not including) 10.0.26200.9711.
• microsoft windows 11 26h1: up to (not including) 10.0.28000.3231.
• microsoft windows 11 26h2: up to (not including) 10.0.26300.9711.
• microsoft windows server 2016: up to (not including) 10.0.14393.9612.

Version ranges come from the NVD CPE configuration. Confirm against the vendor advisory before you rely on them.

• Exploited in the wild: added to the CISA Known Exploited Vulnerabilities catalog on 2026-10-13; federal remediation due date 2026-10-16.

• EPSS (probability of exploitation activity in the next 30 days): 1.51%, higher than 74% of all scored CVEs (as of 2026-10-24).
• CVERadar threat level: 59/100 (see methodology).
• Likely ATT&CK techniques: T1190 Exploit Public-Facing Application (inferred); T1059 Command and Scripting Interpreter (inferred).

1. Find every instance. List where Microsoft Windows runs, including test, DR and forgotten internet-facing systems, and record the installed version.

   # Windows edition and build
   Get-ComputerInfo -Property WindowsProductName, WindowsVersion, OsBuildNumber
   
   # Most recently installed updates
   Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 10 HotFixID, InstalledOn

2. Upgrade to a fixed release. microsoft windows 10 1607: 10.0.14393.9612 or later; microsoft windows 10 1809: 10.0.17763.9376 or later; microsoft windows 10 21h2: 10.0.19044.7807 or later; microsoft windows 10 22h2: 10.0.19045.7807 or later. Get the build from the vendor advisory.

   # After deploying the update through Windows Update, WSUS or Intune,
   # confirm the KB from the Microsoft advisory is installed:
   Get-HotFix -Id <KB-number-from-the-advisory>

3. If you can't patch today, follow CISA's required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
4. Verify the fix. Re-run the version check above on every instance and confirm it reports the fixed build (10.0.14393.9612 or later). Re-scan from outside if the service is exposed.
5. Hunt for signs of earlier compromise. If the system was exposed before you patched, assume it may have been hit and check the items below.
6. Rotate credentials stored on or used by the affected system if you cannot rule out compromise, and keep the logs you reviewed.

Detection hints

• T1190 Exploit Public-Facing Application: Review WAF, reverse-proxy and application logs for unusual requests to Windows (odd paths, oversized or encoded payloads, bursts of errors), going back to at least 2026-10-13.
• T1059 Command and Scripting Interpreter: Watch for the service process spawning shells or script interpreters.

# Process creation events (needs "Audit Process Creation" enabled)
Get-WinEvent -FilterHashtable @{ LogName = 'Security'; Id = 4688 } -MaxEvents 500 |
  Select-Object TimeCreated, Message

Detection commands are generic starting points, not CVE-specific signatures. Use the indicators from the vendor advisory when it publishes them.

• NVD: CVE-2026-96951 nvd.nist.gov/vuln/detail/CVE-2026-96951
• CVE.org record www.cve.org/CVERecord?id=CVE-2026-96951
• Microsoft Security Update Guide msrc.microsoft.com/update-guide/vulnerability/CVE-2026-96951
• Vendor link from CISA KEV msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-96951
• CISA KEV catalog www.cisa.gov/known-exploited-vulnerabilities-catalog
• FIRST EPSS (2026-10-24) api.first.org/data/v1/epss?cve=CVE-2026-96951