Security readout for executives and security teams
This is a critical flaw in Zoho ManageEngine ADSelfService Plus 6113 and earlier. An unauthenticated remote attacker could bypass REST API authentication and achieve code execution. Because CISA lists it in KEV, organizations should treat exposed instances as urgent risk, especially where password self-service systems touch identity infrastructure. Exposure is most likely in organizations running Zoho ManageEngine ADSelfService Plus version 6113 or earlier, particularly internet-accessible password self-service or identity-adjacent portals. Treat this as an immediate remediation item for any affected deployment. The vulnerability combines unauthenticated remote code execution, identity-system proximity, critical CVSS severity, and confirmed KEV listing. Mitigation focus: Identify all ADSelfService Plus instances and confirm running build versions.; Follow ManageEngine’s vendor guidance for the REST API authentication bypass fix.; Prioritize remediation for internet-facing or identity-adjacent deployments..
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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ATT&CK lookup starting points
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CWE-706: Exact CWE lookup
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Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-40539 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.manageengine.com/CVE reference · x_refsource_MISC
- https://www.manageengine.com/products/self-service-password/kb/how-to-fix-authentication-bypass-vulnerability-in-REST-API.htmlCVE reference · x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40539CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use of Incorrectly-Resolved Name or Reference
Use of Incorrectly-Resolved Name or Reference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.