Microsoft Windows: code execution flaw under attack

What is affected

Microsoft Windows is found on ordinary personal computers and phones, so this is not only a problem for companies. If you use it and have not updated since the fix was released, you are exposed.

Microsoft Windows Shell contains a command injection vulnerability that allows an unauthorized attacker to bypass a security feature over a network.

What an attacker can do

This is a code execution flaw. It lets an attacker run their own commands or programs on the affected system. In practice that usually means taking it over: installing malware, stealing data or using it to reach other devices on the same network.

How it is reached

Over the internet or network

Access the attacker needs

No account needed

Does the victim have to do something?

Yes, the victim must open or click something

What to do

1. Update Microsoft Windows now. Open the update or "About" screen, install whatever is offered and restart the app or device, because the fix is not active until you do.
2. Turn on automatic updates so the next fix arrives without you having to look for it.
3. If your device is too old to receive this update, stop using the affected app for anything sensitive and plan a replacement.

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.

Vendor advisories and fixes

• msrc.microsoft.commsrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2026-96951

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on October 13, 2026, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by October 16, 2026 (2 days from now). That deadline does not bind anyone else, but it shows how seriously the agency rates it.

Its CVSS severity score is 8.8 out of 10 (high), as recorded in the US National Vulnerability Database.

Technical description

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.

Guides for this

• Microsoft Defender reviewWhat Windows' own protection catches and when you need more.
• Run a Defender Offline scanChecks Windows before it starts, where malware cannot hide.
• Malware removalIf you think the flaw was used against you: signs and removal.

Follow the story: Windows zero-days under attack

Every Windows flaw CISA confirms is being exploited, as it is added, with our news on Patch Tuesday fixes. What to update and when. 66 events so far, updated Oct 13, 2026.

• CVE-2026-96951 added to CISA's exploited list: Microsoft Windows Command Injection VulnerabilityOct 13, 2026
• Patch Tuesday 2026: Record Fixes, Zero-Days and Next DatesOct 7, 2026
• CVE-2026-85880 added to CISA's exploited list: Microsoft Windows Heap-Based Buffer Overflow VulnerabilitySep 8, 2026

See the full timeline →