CVE-2026-85885: Critical Command Injection in Microsoft 365 Copilot

CVE-2026-85885 is a critical command injection flaw in Microsoft 365 Copilot, scored 9.9. The record says an authorized attacker could elevate privileges over a network, with a changed scope. It lists no versions, so read the Microsoft advisory for the required action and review who has Copilot access.

What's affected

• Product: Microsoft 365 Copilot.
• Affected versions: the record lists none, only the product.
• Fixed versions or required action: stated in the Microsoft Security Response Center entry. That page needs JavaScript and did not load when I fetched it, so check it directly.
• Attack path: network, low privileges, no user interaction, with changed scope (CVSS vector AV:N/AC:L/PR:L/UI:N/S:C).

Severity in the record: Critical, CVSS 9.9 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H).

Weakness class: CWE-77 (Command Injection).

How to check if you're exposed

The record gives no version details, so there is no command to run. Use these steps.

1. Open the Microsoft Security Update Guide entry for CVE-2026-85885 and read the sections on affected products and required customer action.
2. Many Microsoft 365 services are updated by Microsoft rather than by the customer. Check whether the entry says anything is needed from your side.
3. Review which users and service accounts have Copilot licenses and access. The record says an authorized user is required.
4. Check your admin audit logs for unusual Copilot activity from low privilege accounts.

What to do now

1. Read the MSRC entry and record whether the fix was applied by Microsoft or needs action from your tenant.
2. Review Copilot license assignment, and remove access for people who do not need it.
3. Check tenant audit logs for unusual Copilot related events and escalation of privileges.
4. Review what data and connectors Copilot can reach, and narrow permissions where they are broad.
5. Subscribe to Microsoft security notifications so you see updates to this entry.

Why it matters

Command injection means untrusted text reaches a place that treats it as an instruction. The record tags the weakness as CWE-77. It gives little more, which is typical for Microsoft entries.

The score is 9.9 because the attack is low complexity, needs only low privileges, and has a changed scope, meaning the impact reaches beyond the vulnerable component. High confidentiality, integrity and availability impacts complete the picture. That is the only reason this entry is Critical. The record does not mark it as exploited in the wild, and it is not on the CISA list. For a hosted product, the first question is whether anything is required of you.

Quick check

Sources

• Microsoft Security Update Guide entry

Last reviewed: 18 October 2026.