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

Source: https://junglewise.ai/threats/cve-2021-40539-zoho-manageengine-adselfservice-plus-authentication-bypass  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-11-03. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2021-40539 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2021-11-03

Zoho ManageEngine ADSelfService Plus is vulnerable to an authentication bypass affecting REST API URLs. Successful exploitation allows an unauthenticated remote attacker to execute arbitrary code on the system.

Technologies: [Zoho ManageEngine](https://junglewise.ai/threats/technologies/manageengine). Vendors: [Zoho](https://junglewise.ai/threats/vendors/zoho).

## Quick answers

**Is CVE-2021-40539 exploited in the wild?** Yes. CVE-2021-40539 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.

**How severe is CVE-2021-40539?** Critical severity, with a CVSS score of 9.8, published 3 November 2021.

**Which products and versions are affected?** Zoho Corp ManageEngine ADSelfService Plus 6113 and prior.

**Is there a fix for CVE-2021-40539?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2021-40539 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2021-40539?** Check whether you run Zoho ManageEngine. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Zoho Corp ManageEngine ADSelfService Plus 6113 and prior

## Timeline

- 2021-11-03: disclosed
- 2021-11-03: kev added: Added to CISA Known Exploited Vulnerabilities Catalog

## Related threats

- [Zoho ManageEngine ADSelfService Plus Remote Code Execution Vulnerability](https://junglewise.ai/threats/cve-2022-28810-zoho-manageengine-adselfservice-plus-remote-code-execution)
- [Zoho ManageEngine Multiple Products Remote Code Execution Vulnerability](https://junglewise.ai/threats/cve-2022-47966-zoho-manageengine-multiple-products-remote-code-execution)
- [Zoho ManageEngine Multiple Products Remote Code Execution Vulnerability](https://junglewise.ai/threats/cve-2022-35405-zoho-manageengine-multiple-products-remote-code-execution)
- [Zoho ManageEngine ServiceDesk Plus (SDP) File Upload Vulnerability](https://junglewise.ai/threats/cve-2019-8394-zoho-manageengine-servicedesk-plus-sdp-file-upload-vulnerability)
- [Zoho ManageEngine Desktop Central File Upload Vulnerability](https://junglewise.ai/threats/cve-2020-10189-zoho-manageengine-desktop-central-file-upload-vulnerability)