Hazard

Is CVE-2021-40539 being exploited?

Ransomware crews are using this

CISA has linked this vulnerability to known ransomware campaigns. Treat any exposed instance as an active incident, not a patching ticket.

Zoho ManageEngine ADSelfService Plus Authentication Bypass Vulnerability

Zoho · ManageEngine

CVSS 9.8 EPSS 99% no public exploit indexed ransomware Fix deadline passed 17 November 2021

What it is

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

Why we say that

  • Linked by CISA to known ransomware campaigns
  • EPSS puts exploitation in the next 30 days at 99%
  • CISA's federal remediation deadline (2021-11-17) has passed
  • CVSS 9.8 critical
  • Listed in the CISA Known Exploited Vulnerabilities catalogue

Every line above comes from a named public source. Where the evidence is thin, we say so rather than inventing confidence — see methodology.

What to do

Apply updates per vendor instructions.

What it costs when this goes wrong

This is where UK enforcement meets the vulnerability record. This vulnerability is used in ransomware campaigns; here is what ransomware has cost UK organisations at the regulator.

All UK cases caused by ransomware →