CVE-2021-40539
Zohocorp Manageengine Adselfservice Plus ≤ 6.1
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2021-40539 is a critical-severity Use of Incorrectly-Resolved Name or Reference (CWE-706) vulnerability in Zohocorp Manageengine Adselfservice Plus. Its CVSS base score is 9.8 (Critical).
Operationally, ranked in the top 0.1% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
Zoho ManageEngine ADSelfService Plus versions 6113 and earlier contain a REST API authentication bypass vulnerability that leads directly to remote code execution. The flaw is tracked as CVE-2021-40539 and carries a CVSS 3.1 base score of 9.8, reflecting network-accessible exploitation without credentials or user interaction. The affected component is the product's REST API handling, classified under CWE-706.
Unauthenticated attackers can send specially crafted requests to the REST endpoints to circumvent authentication controls and obtain the ability to execute arbitrary code on the underlying server. Successful exploitation grants full control over the ManageEngine instance, including access to stored credentials and the ability to pivot within the managed Active Directory environment.
Vendor guidance published by ManageEngine directs administrators to apply the authentication bypass fix for the REST API; the company has released a knowledge-base article detailing the required remediation steps along with updated builds that address the issue. Public exploit code for the vulnerability has also been posted to Packet Storm.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-27714
Vulnerability Data
Zoho ManageEngine ADSelfService Plus version 6113 and prior is vulnerable to REST API authentication bypass with resultant remote code execution.
- CWE(s)
- KEV Date Added
- 03 November 2021
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Threat-Actor AttributionAI
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Affected Assets
Mitigating Controls
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Network segmentation and routing policies reduce the chance that a mis-resolved name leads to an unintended external resource.
Segregated networks limit the blast radius when a name or reference resolves outside the intended control sphere.
Secure SDLC practices include design reviews that can catch incorrect name or reference handling before deployment.
A.8.26 only requires that security requirements (including those that could address name-resolution issues) be identified during development or acquisition; it does not itself enforce, implement, or stop exploitation of an incorrectly-resolved name or reference.
A.8.27 mandates security-by-design principles (least privilege, default-deny, distrust-external-input, security-oriented design reviews, hardening) that reach many but not all name-resolution mistakes; a bounded remainder (e.g. flawed resolution logic inside trusted components or libraries) can still be introduced and exploited.
Secure-coding standards directly address canonicalization, input validation and safe name resolution, mitigating CWE-706.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.
- No fine-grained STIG row for CWE-706, a class-level weakness, and none of its children carries one either.