What is CVE-2021-42099?

CVE-2021-42099 is a critical-severity vulnerability in Zohocorp Manageengine M365 Manager Plus, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2021-11-30.

How severe is CVE-2021-42099?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Arbitrary file upload in Zohocorp Manageengine M365 Manager Plus

CVE-2021-42099

Zoho ManageEngine M365 Manager Plus before 4421 is vulnerable to file-upload remote code execution.

Vulnerability class: Unrestricted File Upload

Published 2021-11-30 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.068 (93.8th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 94th percentile — 93.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.065 · newest: 0.068 · change: +0.002

Affected products

Zohocorp Manageengine M365 Manager Plus — versions build_4000, build_4001, build_4002

Weakness classification (CWE)

CWE-434 — Unrestricted Upload of File with Dangerous Type

References

www.manageengine.com (Product)
www.manageengine.com/microsoft-365-management-reporting/release-notes.html (Release Notes, Vendor Advisory)

Frequently asked questions

What is CVE-2021-42099?: CVE-2021-42099 is a critical-severity vulnerability in Zohocorp Manageengine M365 Manager Plus, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 9.8/10. Published 2021-11-30.
How severe is CVE-2021-42099?: Critical severity. CVSS v3 base score is 9.8 out of 10.