What is CVE-2026-78501?

CVE-2026-78501 is a high-severity vulnerability in Microsoft 365 Copilot's Business Chat, classified under Command Injection. CVSS score: 7.4/10. Published 2026-09-17.

How severe is CVE-2026-78501?

High severity. CVSS v3 base score is 7.4 out of 10.

RCE in Microsoft 365 Copilot's Business Chat

CVE-2026-78501

Improper neutralization of special elements used in a command ('command injection') in Microsoft 365 Copilot's Business Chat allows an unauthorized attacker to disclose information over a network.

Vulnerability class: Command Injection (OS Command Injection)

CVSS v3 metric

CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N.

Affected products

Microsoft 365 Copilot's Business Chat

Weakness classification (CWE)

CWE-77 — Command Injection
CWE-923

References

secure@microsoft.com (vendor-advisory, patch)

Frequently asked questions

What is CVE-2026-78501?: CVE-2026-78501 is a high-severity vulnerability in Microsoft 365 Copilot's Business Chat, classified under Command Injection. CVSS score: 7.4/10. Published 2026-09-17.
How severe is CVE-2026-78501?: High severity. CVSS v3 base score is 7.4 out of 10.