What is CVE-2026-42827?

CVE-2026-42827 is a medium-severity vulnerability in Microsoft 365_copilot, classified under Command Injection. CVSS score: 6.5/10. Published 2026-05-22.

How severe is CVE-2026-42827?

Medium severity. CVSS v3 base score is 6.5 out of 10.

RCE in Microsoft 365_copilot

CVE-2026-42827

Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an unauthorized attacker to disclose information over a network.

Vulnerability class: Command Injection (OS Command Injection)

EPSS: 0.001 (21.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.

Affected products

Microsoft 365_copilot
Microsoft 365 Copilot

Weakness classification (CWE)

CWE-77 — Command Injection

References

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

Frequently asked questions

What is CVE-2026-42827?: CVE-2026-42827 is a medium-severity vulnerability in Microsoft 365_copilot, classified under Command Injection. CVSS score: 6.5/10. Published 2026-05-22.
How severe is CVE-2026-42827?: Medium severity. CVSS v3 base score is 6.5 out of 10.