CVE-2025-52691
Published 2025-12-29 · Updated 2026-10-07 · Source 5f57b9bf-260d-4433-bf07-b6a79e9bb7d4
Summary
CVE-2025-52691 is a critical-severity (CVSS 10.0) vulnerability in SmarterTools SmarterMail. CISA added it to the Known Exploited Vulnerabilities catalog on January 26, 2026, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by February 16, 2026. CISA also lists it as known to be used in ransomware campaigns, so it should be prioritised accordingly. SmarterTools has 3 vulnerabilities in the KEV catalog, 3 of them linked to ransomware.
All 3 known-exploited SmarterTools vulnerabilities →Description
Successful exploitation of the vulnerability could allow an unauthenticated attacker to upload arbitrary files to any location on the mail server, potentially enabling remote code execution.
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CISA Known-Exploited Vulnerability
Product: SmarterTools — SmarterMail
Name: SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type Vulnerability
Date added: 2026-01-26 · Due: 2026-02-16
Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.