What is CVE-2026-21520?

CVE-2026-21520 is a high-severity vulnerability in Microsoft Copilot Studio, classified under Command Injection. CVSS score: 7.5/10. Published 2026-01-22.

How severe is CVE-2026-21520?

High severity. CVSS v3 base score is 7.5 out of 10.

RCE in Microsoft Copilot Studio

CVE-2026-21520

Exposure of Sensitive Information to an Unauthorized Actor in Copilot Studio allows a unauthenticated attacker to view sensitive information through network attack vector

Vulnerability class: Command Injection (OS Command Injection)

Published 2026-01-22 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.015 (73.0th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 73rd percentile — 73.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.014 · newest: 0.015 · change: +0.001

Affected products

Weakness classification (CWE)

CWE-77 — Command Injection

References

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

Frequently asked questions

What is CVE-2026-21520?: CVE-2026-21520 is a high-severity vulnerability in Microsoft Copilot Studio, classified under Command Injection. CVSS score: 7.5/10. Published 2026-01-22.
How severe is CVE-2026-21520?: High severity. CVSS v3 base score is 7.5 out of 10.