CVE-2026-96951: Microsoft Windows Command Injection Vulnerability

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Yes, if you run Microsoft Windows. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-10-13, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-10-16; treat that as the outer limit, not the target.
• EPSS 1.5%, percentile 74: FIRST’s model estimates a 1.5% chance of exploitation activity in the next 30 days, higher than 74% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Needs a user to click or open something. Phishing makes that realistic, but it is not wormable.
• Editorial verdict: Patch this week. Windows Shell CVE-2026-96951: Exploited MOTW Bypass — Roll the October 2026 Windows update out to every desktop this week; attackers are using this to make malicious attachments and downloads skip the warnings that would stop them.

What it is

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.

CISA’s summary

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

Weakness type: CWE-77.

Product: Microsoft Windows · Assigned by: microsoft · Published: 2026-10-13

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: required (a user must click/open something)
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: added 2026-10-13; federal due date 2026-10-16. Known ransomware use: Unknown.
• CISA 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.
• CISA SSVC assessment: exploitation active, automatable no, technical impact total.
• FIRST EPSS (model of 2026-10-21): 1.51% probability of exploitation activity in the next 30 days; percentile 74.

Timeline

• 2026-10-13 — Added to CISA’s Known Exploited Vulnerabilities catalog
• 2026-10-13 — CVE record published by microsoft
• 2026-10-13 — erroneo.us brief: Windows Shell CVE-2026-96951: Exploited MOTW Bypass
• 2026-10-16 — CISA remediation deadline for US federal agencies
• 2026-10-21 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. Windows Shell Security Feature Bypass Vulnerability msrc.microsoft.com
2. Listed in CISA KEV notes (msrc.microsoft.com) msrc.microsoft.com

Vulnerability records

1. CVE.org record CVE-2026-96951 cve.org
2. NVD entry CVE-2026-96951 nvd.nist.gov

Government

1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov

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