Hazard

Is CVE-2026-24423 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.

SmarterTools SmarterMail Missing Authentication for Critical Function Vulnerability

SmarterTools · SmarterMail

CVSS 9.3 EPSS 88% no public exploit indexed ransomware Fix deadline passed 26 February 2026

What it is

SmarterTools SmarterMail contains a missing authentication for critical function vulnerability in the ConnectToHub API method. This could allow the attacker to point the SmarterMail instance to a malicious HTTP server which serves the malicious OS command and could lead to command execution.

Why we say that

  • Linked by CISA to known ransomware campaigns
  • EPSS puts exploitation in the next 30 days at 88%
  • CISA's federal remediation deadline (2026-02-26) has passed
  • CVSS 9.3 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 mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

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 →