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Fencer Vulns
critical 9.8

CVE-2021-40539 kev+ ransomware in the critical feed json

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

published 2021-09-07 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-27714

cvss
9.8
version 3.1, CNA
cisa kev
Exploited
added 2021-11-03, used in ransomware
epss
99.0%
EPSS 99.0% chance of exploitation in 30 days, percentile 99.9%
public exploits
1
Metasploit, plus a Nuclei check

Summary

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

Patch / fix

cisa required action Apply updates per vendor instructions.

  • zohocorp manageengine_adselfservice_plus 6.1

Timeline

  1. First public exploit (Metasploit exploit/windows/http/manageengine_adselfservice_plus_cve_2021_40539)
  2. Published
  3. Added to CISA KEV
  4. CISA patch deadline
  5. CISA SSVC: exploitation active

Known exploited

Added
5 y ago
Patch by
2021-11-17 (4 y ago)
Ransomware
Known to be used in ransomware campaigns
Required action
Apply updates per vendor instructions.
Vendor, product
Zoho, ManageEngine
CISA name
Zoho ManageEngine ADSelfService Plus Authentication Bypass Vulnerability

Ransomware

Groups reported to have exploited it in intrusions.

  • AvosLocker ransomware gang
  • Trigona ransomware gang

reported by kroll.comareteir.com

Ransomware Vulnerability Matrix by BushidoUK (github.com/BushidoUK/Ransomware-Vulnerability-Matrix), reformatted per CVE. CC BY 4.0

ATT&CK techniques

How it is exploited and what it leads to, in MITRE ATT&CK terms.

  • T1190 Exploit Public-Facing Application exploitation
  • T1505.003 Web Shell primary impact
  • T1003 OS Credential Dumping secondary impact
  • T1003.003 NTDS secondary impact
  • T1027 Obfuscated Files or Information secondary impact
  • T1047 Windows Management Instrumentation secondary impact
  • T1070.004 File Deletion secondary impact
  • T1087.002 Domain Account secondary impact
  • T1136 Create Account secondary impact
  • T1140 Deobfuscate/Decode Files or Information secondary impact
  • T1218 System Binary Proxy Execution secondary impact
  • T1505.003 Web Shell secondary impact
  • T1560.001 Archive via Utility secondary impact
  • T1573.001 Symmetric Cryptography secondary impact

kev release 2025-07-28, att&ck v16.1. KEV to ATT&CK mappings by the MITRE Center for Threat-Informed Defense (Mappings Explorer, Apache-2.0). © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. Terms of use

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
21 mo ago

Exploit prediction

98.96% chance of exploitation in the next 30 days, higher than 99.9% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Classification

Weakness
  • CWE-706 Use of Incorrectly-Resolved Name or Reference

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.