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

> Attackers can bypass REST API authentication to achieve remote code execution on Zoho ManageEngine ADSelfService Plus servers.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Yes, since 3 Nov 2021 (CISA KEV), used in ransomware
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Sep 2021
- **Updated:** 21 Oct 2025
- **Also known as:** GHSA-gww8-rh9f-5mjq

## What is CVE-2021-40539?

CVE-2021-40539 is a critical authentication bypass vulnerability in Zohocorp Manageengine Adselfservice Plus, published on 7 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

Weakness: CWE-706 (Use of Incorrectly-Resolved Name or Reference)

## Which versions are affected by CVE-2021-40539?

It affects 1 product.


Products: Zohocorp Manageengine Adselfservice Plus.

## How do I fix CVE-2021-40539?

No fix has been published for CVE-2021-40539 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 17 Nov 2021.

## Is CVE-2021-40539 being exploited?

Yes. Attackers have exploited CVE-2021-40539 in the wild since at least 3 Nov 2021, including in ransomware campaigns.

Public exploit code:

- Exploitation code for CVE-2021-40539 (github_poc): https://github.com/synacktiv/CVE-2021-40539
- CVE-2021-40539 POC (github_poc): https://github.com/DarkSprings/CVE-2021-40539
- ADSelfService Plus RCE漏洞 检测工具 (二开) (github_poc): https://github.com/Bu0uCat/ADSelfService-Plus-RCE-CVE-2021-40539
- CVE-2021-40539：ADSelfService Plus RCE漏洞 (github_poc): https://github.com/lpyydxs/CVE-2021-40539
- ManageEngine ADSelfService Plus CVE-2021-40539 (metasploit)
- CVE-2021-40539：ADSelfService Plus RCE漏洞 (github_poc): https://github.com/lpyzds/CVE-2021-40539

## Other vulnerabilities in Zohocorp Manageengine Adselfservice Plus

- [CVE-2022-28810](https://insights.sbomify.com/CVE-2022-28810/): Zoho ManageEngine ADSelfService Plus Remote Code Execution (medium 6.8, exploited in the wild)
- [CVE-2019-3905](https://insights.sbomify.com/CVE-2019-3905/): Server-side request forgery in n/a (critical 10.0)
- [CVE-2023-35854](https://insights.sbomify.com/CVE-2023-35854/): Auth bypass in n/a (critical 9.8)
- [CVE-2021-37422](https://insights.sbomify.com/CVE-2021-37422/): SQL injection in n/a (critical 9.8)
- [CVE-2021-37423](https://insights.sbomify.com/CVE-2021-37423/): Auth bypass in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-40539 and fix it if it is affected.

What it is: CVE-2021-40539 is a critical authentication bypass vulnerability in Zohocorp Manageengine Adselfservice Plus, published on 7 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2021-40539 in the wild since at least 3 Nov 2021, including in ransomware campaigns.

Affected product: Zohocorp Manageengine Adselfservice Plus. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-40539/ (Markdown: https://insights.sbomify.com/CVE-2021-40539/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-40539
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-40539
- OSV: https://osv.dev/vulnerability/CVE-2021-40539

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-40539/
Summaries are generated and may contain mistakes; the official description above is the record.