CVE-2021-40539
CriticalExploitedPublic exploitZoho ManageEngine ADSelfService Plus version 6113 and prior is vulnerable to REST API authentication bypass with resultant remote code execution.
Published Jan 18, 2022 · Updated Oct 21, 2025 · Also known as TR-22-0055
Key Facts
Patch immediately- CVE-2021-40539 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Manageengine Adselfservice Plus (Zohocorp).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Sep 16, 2021 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 99% probability of exploitation in the next 30 days.
- Fixed versions are available, including Manageengine Adselfservice Plus 6.1.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
99%
Higher than 99.9% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2021-40539 brief as a PDF
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Description
Zoho ManageEngine ADSelfService Plus version 6113 and prior is vulnerable to REST API authentication bypass with resultant remote code execution.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | Nov 17, 2021 | Known |
| Industry KEV feed | Sep 16, 2021 | Nov 17, 2021 | Known |
| CIRCL KEV | Nov 3, 2021 | Nov 17, 2021 | Known |
| ENISA EUVD | Nov 3, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
10 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Manageengine Adselfservice PlusZohocorp | 6.1, 6.1-6100, 6.1-6101, 6.1-6102, 6.1-6103, 6.1-6104, 6.1-6105, 6.1-6106 | 6.1 |
Patched Releases
Manageengine Adselfservice Plus
6.1
Timeline
Added to Industry KEV feed
Sep 16, 2021
Added to CISA KEV
Nov 3, 2021
Added to CIRCL KEV
Nov 3, 2021
Added to ENISA EUVD
Nov 3, 2021
Publicly disclosed
Jan 18, 2022
Last updated
Oct 21, 2025
Weakness Type
- CWE-706 Use of Incorrectly-Resolved Name or Reference
References
- advisoryhttp://feedproxy.google.com/
- advisoryhttps://blogs.vmware.com/vsphere/2021/09/vmsa-2021-0020-what-you-need-to-know.html
- advisoryhttps://blog.talosintelligence.com/2021/11/microsoft-patch-tuesday-for-nov-2021.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+feedburner/Talos+(Talos%E2%84%A2+Blog)Microsoft
- advisoryhttps://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-40539
- advisoryhttps://helpx.adobe.com/security/products/incopy/apsb21-110.html
FAQ
Common Questions.
Zoho ManageEngine ADSelfService Plus version 6113 and prior is vulnerable to REST API authentication bypass with resultant remote code execution.
Affected: Manageengine Adselfservice Plus (Zohocorp) versions 6.1, 6.1-6100, 6.1-6101, 6.1-6102, 6.1-6103, 6.1-6104, 6.1-6105, 6.1-6106. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Sep 16, 2021 and is known to be used in ransomware campaigns.
Yes. It was added on Nov 3, 2021 with a federal remediation due date of Nov 17, 2021.
Public exploit code is available.
Fixed versions are available, including Manageengine Adselfservice Plus 6.1.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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