Is CVE-2021-40539 actively exploited?

Yes. CVE-2021-40539 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, which means exploitation in the wild has been confirmed.

Can CVE-2021-40539 be exploited remotely?

The attack vector of CVE-2021-40539 has not been classified yet.

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

CVE-2021-40539 has not received a CVSS score yet.

HOME VULNERABILITIESCVE-2021-40539

HIGHCISA KEVIN THE WILD

CVE-2021-40539

Published: November 3, 2021

EPSS:94.42%probability of exploitation in 30 daysPercentile:100.0th

Official Description

Zoho ManageEngine ADSelfService Plus contains an authentication bypass vulnerability affecting the REST API URLs which allow for remote code execution.

NVD Source

CISA KEV Advisory

Zoho ManageEngine ADSelfService Plus Authentication Bypass Vulnerability

Zoho ManageEngine ADSelfService Plus contains an authentication bypass vulnerability affecting the REST API URLs which allow for remote code execution.

Added to KEV: 2021-11-03Federal patch deadline: 2021-11-17⚠ USED IN RANSOMWARE CAMPAIGNS

Required Action (CISA)

Apply updates per vendor instructions.

Risk Analysis

Zoho ManageEngine ADSelfService Plus contains an authentication bypass vulnerability affecting REST API URLs, which can lead to remote code execution. This critical flaw, with its high EPSS score and confirmed exploitation, poses an immediate and severe risk. Attackers can bypass authentication to execute arbitrary code.

This vulnerability is actively exploited in the wild and is included in CISA's KEV catalog, confirming its use by threat actors. The authentication bypass affects REST API URLs, making it remotely exploitable for code execution.

Recommended Action

Administrators of Zoho ManageEngine ADSelfService Plus should immediately apply the latest security updates to patch this authentication bypass and remote code execution vulnerability. Reviewing and restricting access to REST API endpoints is also recommended.

Generated by the CTIWATCH analysis pipeline from this CVE's metadata (CVSS, EPSS, KEV status, exploit intelligence). Verify against vendor advisories before acting.

Technical Analysis

CVE-2021-40539 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

CISA has added CVE-2021-40539 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.