CVE entry · CVE-2025-52691
CVE-2025-52691: SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type Vulnerability
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.
- Actively exploited: added to CISA’s KEV catalog on January 26, 2026.
- Used by ransomware, according to CISA.
- Remediation deadline for US federal agencies: February 16, 2026.
Description from CISA’s KEV catalog.
What to do
- Check whether your estate includes SmarterTools SmarterMail, including internet-facing devices.
- Apply the vendor’s patch or mitigations (references below). Failing that, isolate the product or stop using it, as CISA requires of US federal agencies.
- An exploited vulnerability has often been used before it was fixed: look for signs of compromise, especially on internet-facing devices.
References
- Vendor advisory or reference cited by CISA (www.smartertools.com)
- Vendor advisory or reference cited by CISA (www.csa.gov.sg)
- NVD entry (NIST)
- CISA KEV catalog