CVE-2026-26164

Severity CVSS v4.0:

Pending analysis

Type:

CWE-74 Injection

Publication date:

07/05/2026

Last modified:

08/05/2026

Description

Improper neutralization of special elements in output used by a downstream component (&#39;injection&#39;) in M365 Copilot allows an unauthorized attacker to disclose information over a network.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N CVSS v3.1 Severity and Metrics:

Base Score: 7.50 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): None
Availability (A): None

Base Score 3.x

7.50

Severity 3.x

HIGH

Vulnerable products and versions

CPE	From	Up to
cpe:2.3:a:microsoft:365_copilot_chat:-:::::::*

To consult the complete list of CPE names with products and versions, see this page

References to Advisories, Solutions, and Tools

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26164