What is CVE-2021-33055?

CVE-2021-33055 is a critical-severity vulnerability in Microsoft Windows, classified under OS Command Injection. CVSS score: 9.8/10. Published 2021-08-30.

How severe is CVE-2021-33055?

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

Is CVE-2021-33055 known to be exploited?

3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

RCE in Microsoft Windows

CVE-2021-33055

Zoho ManageEngine ADSelfService Plus through 6102 allows unauthenticated remote code execution in non-English editions.

Vulnerability class: Command Injection (OS Command Injection)

Published 2021-08-30 · 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: 0.181 (97.1th percentile), scored 2026-09-30.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 97th percentile — 97.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.181 · newest: 0.181 · change: 0.000

Affected products

Microsoft Windows
Zohocorp Manageengine Adselfservice Plus — versions 6.1

Weakness classification (CWE)

CWE-78 — OS Command Injection

Public proof-of-concept exploits

References

blog.stmcyber.com/vulns/cve-2021-33055/ (Third Party Advisory, Release Notes)
pitstop.manageengine.com/portal/en/community/topic/adselfservice-plus-6104-rele… (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-33055?: CVE-2021-33055 is a critical-severity vulnerability in Microsoft Windows, classified under OS Command Injection. CVSS score: 9.8/10. Published 2021-08-30.
How severe is CVE-2021-33055?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2021-33055 known to be exploited?: 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.