What is the CVSS score of CVE-2021-40539?

CVE-2021-40539 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 99.0%.

Is there a public PoC exploit available for CVE-2021-40539?

Yes, a public proof-of-concept exploit is available for CVE-2021-40539. Prioritise patching immediately. EPSS: 99.0%.

Is there a patch available for CVE-2021-40539?

Yes, a patch is available for CVE-2021-40539. Update the affected software to the latest version immediately.

Zoho CVE-2021-40539

CRITICAL

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

2021-09-07 cve@mitre.org

RCE Zoho Authentication Bypass Manageengine Adselfservice Plus

9.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

9.8 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Added to CISA KEV

Jul 14, 2026 - 04:22 CISA

CVE Published

Sep 07, 2021 - 17:15 nvd

CRITICAL 9.8

DescriptionNVD

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

AnalysisAI

Zoho ManageEngine ADSelfService Plus version 6113 and prior is vulnerable to REST API authentication bypass with resultant remote code execution. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available.

Technical ContextAI

This vulnerability is classified under CWE-706. Zoho ManageEngine ADSelfService Plus version 6113 and prior is vulnerable to REST API authentication bypass with resultant remote code execution. Affected products include: Zohocorp Manageengine Adselfservice Plus. Version information: version 6113.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.