# CVE-2021-40539: Zoho ManageEngine ADSelfService Plus Authentication Bypass Vulnerability

> CVE-2021-40539: Zoho ManageEngine ADSelfService Plus Authentication Bypass Vulnerability. CVSS 9.8 (CVSS 3.1), in CISA KEV.

Canonical: https://rewindex.com/cve/CVE-2021-40539
Last updated: 2025-10-21T23:25:35Z

- Published: 2021-09-07 16:06 UTC · Updated: 2025-10-21 23:25 UTC · Assigner: mitre
- CVSS: 9.8 (CVSS 3.1) · Severity: Critical · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS: 99.0%, 100th percentile (scored 2026-10-25)
- CISA KEV: yes, added 2021-11-03, federal due date 2021-11-17, ransomware use: Known

## Description

Zoho ManageEngine ADSelfService Plus version 6113 and prior is vulnerable to REST API authentication bypass with resultant remote code execution.

## CISA required action

Apply updates per vendor instructions.

## Affected vendors and products

- Zoho: ManageEngine

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2021-40539)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2021-40539)
- [http://packetstormsecurity.com/files/165085/ManageEngine-ADSelfService-Plus-Authentication-Bypass-Code-Execution.html](http://packetstormsecurity.com/files/165085/ManageEngine-ADSelfService-Plus-Authentication-Bypass-Code-Execution.html)
- [https://www.manageengine.com](https://www.manageengine.com)
- [https://www.manageengine.com/products/self-service-password/kb/how-to-fix-authentication-bypass-vulnerability-in-REST-API.html](https://www.manageengine.com/products/self-service-password/kb/how-to-fix-authentication-bypass-vulnerability-in-REST-API.html)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2021-40539 · Markdown: https://rewindex.com/cve/CVE-2021-40539.md · JSON: https://rewindex.com/api/v1/cves/CVE-2021-40539 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T02:48:28.427Z