---
id: CVE-2026-50517
title: Microsoft M365 Copilot Remote Code Execution Vulnerability
summary: >-
  Deserialization of untrusted data in M365 Copilot allows an authorized
  attacker to execute code over a network.
severity: critical
cvss: 9.9
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C'
cvssSource: cna
cwe:
  - CWE-502
vendor: Microsoft
product: Microsoft 365 Copilot
affected:
  - 365_copilot -
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-07-24T00:00:00+00:00'
published: '2026-07-24'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T18:25:38.093Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-50517'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50517'
    label: Microsoft M365 Copilot Remote Code Execution Vulnerability
tags:
  - cve.org
epss: 0.01694
epssPercentile: 0.76148
ingestedAt: '2026-09-08T17:06:31.893Z'
---

## Overview

Deserialization of untrusted data in M365 Copilot allows an authorized attacker to execute code over a network.

## Affected

- `365_copilot -`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.