SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type Vulnerability (CVE-2025-52691)
Severity: critical · Patch status: unknown · Since 2026-01-26 · CVE-2025-52691
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. CISA added CVE-2025-52691 to its Known Exploited Vulnerabilities catalog on Jan 26, 2026, which means attackers are exploiting it in the wild. CISA reports known use in ransomware campaigns.
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.
- US federal agencies must remediate by Feb 16, 2026 (BOD 22-01); treat that as the outer limit.
Sources
All live incidents on Threat Watch