What is CVE-2026-85887?

CVE-2026-85887 is a high-severity vulnerability in Microsoft 365 Copilot, classified under Incorrect Permission Assignment for Critical Resource. CVSS score: 7.7/10. Published 2026-09-18.

How severe is CVE-2026-85887?

High severity. CVSS v3 base score is 7.7 out of 10.

Vulnerability in Microsoft 365 Copilot

CVE-2026-85887

Incorrect permission assignment for critical resource in M365 Copilot allows an authorized attacker to disclose information over a network.

Published 2026-09-18 · last modified 2026-09-28.

CVSS v3 metric

CVSS v3 base score 7.7 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.008 (57.9th percentile), scored 2026-11-02.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 57.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-732 — Incorrect Permission Assignment for Critical Resource

References

M365 Copilot Information Disclosure Vulnerability (vendor-advisory, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-85887?: CVE-2026-85887 is a high-severity vulnerability in Microsoft 365 Copilot, classified under Incorrect Permission Assignment for Critical Resource. CVSS score: 7.7/10. Published 2026-09-18.
How severe is CVE-2026-85887?: High severity. CVSS v3 base score is 7.7 out of 10.