SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type Vulnerability

[ Why it matters ]Priority signals

• Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2026-01-26
• Known to be used in ransomware campaigns
• EPSS: 86% chance of exploitation in the next 30 days (higher than 100% of CVEs)
• Critical severity: CVSS 10.0

[ Description ]Official 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.

CISA: 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.

[ Fixes ]Fixes and patches

CISA required action (US federal deadline 16 Feb 2026): Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ References ]References

• www.csa.gov.sg/alerts-and-advisories/alerts/al-2025-124Third Party Advisory
• github.com/watchtowrlabs/watchTowr-vs-SmarterMail-CVE-2025-52691ExploitThird Party Advisory
• www.cisa.gov/known-exploited-vulnerabilities-catalogUS Government Resource