Hazard

Is CVE-2025-52691 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 Unrestricted Upload of File with Dangerous Type Vulnerability

SmarterTools · SmarterMail

CVSS 10 EPSS 85% no public exploit indexed ransomware Fix deadline passed 16 February 2026

What it is

SmarterTools SmarterMail contains an unrestricted upload of file with dangerous type vulnerability that could allow an unauthenticated attacker to upload arbitrary files to any location on the mail server, potentially enabling remote code execution.

Why we say that

  • Linked by CISA to known ransomware campaigns
  • EPSS puts exploitation in the next 30 days at 85%
  • CISA's federal remediation deadline (2026-02-16) has passed
  • CVSS 10 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 →