PatchSiren cyber security CVE debrief

CVE-2026-41090 Microsoft CVE debrief

A critical command injection vulnerability in Microsoft Copilot enables network-based tampering by unauthenticated attackers. The flaw stems from improper neutralization of special elements in commands (CWE-77), allowing malicious input to execute unintended system commands. With a CVSS 3.1 score of 9.3, this vulnerability presents severe risk due to its network attack vector, low complexity, and high impact on confidentiality and integrity across changed scope. The vulnerability was disclosed by Microsoft through their Security Response Center and entered NVD's Undergoing Analysis status on initial publication. No known exploitation in ransomware campaigns has been documented, and the vulnerability has not been added to CISA's Known Exploited Vulnerabilities catalog. Organizations using Microsoft Copilot should prioritize obtaining and deploying security updates from Microsoft once available, as command injection in AI assistant interfaces can expose backend systems and user data to remote manipulation.

Vendor: Microsoft
Product: Microsoft 365 Copilot for iOS
CVSS: CRITICAL 9.3
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-05-22
Original CVE updated: 2026-05-27
Advisory published: 2026-05-22
Advisory updated: 2026-05-27

Who should care

Organizations deploying Microsoft Copilot for enterprise use, security teams managing AI assistant infrastructure, and administrators responsible for Microsoft 365 security posture.

Technical summary

The vulnerability exists in Microsoft Copilot's handling of command inputs, where special elements are not properly neutralized before execution. An unauthenticated attacker can exploit this over the network with low attack complexity, requiring user interaction but no privileges. Successful exploitation enables high-impact tampering affecting confidentiality and integrity with changed scope, though availability impact is not rated. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N) indicates network exploitability with significant blast radius potential.

Defensive priority

critical

Recommended defensive actions

Monitor Microsoft Security Response Center (MSRC) for security update availability and deployment guidance
Review Microsoft Copilot deployment configurations to identify exposure to untrusted network inputs
Implement network segmentation for Copilot instances where possible pending patch availability
Establish monitoring for anomalous command execution patterns in Copilot backend infrastructure
Validate input sanitization controls in any custom integrations with Microsoft Copilot APIs

Evidence notes

Official vulnerability database record from NVD with Microsoft MSRC reference; vendor attribution based on [email protected] source reference; CVSS vector and CWE classification from primary source; status remains Undergoing Analysis per NVD metadata.

Official resources

2026-05-22