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CVE-2025-52691: SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type Vulnerability

criticalknown exploitedpublic exploitCVE-2025-52691
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
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.

CSIRTS triage

vendor: SmarterToolsproduct: SmarterMailRemote code execution
What
An unrestricted file upload vulnerability could allow unauthenticated attackers to upload arbitrary files.
Who is affected
Deployments of SmarterMail are affected.
Urgency
Immediate remediation is necessary due to active exploitation and critical severity.
Action
Update to the latest version of SmarterMail.

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Details

Source
CISA Known Exploited Vulnerabilities (US · database · site)
Severity
critical
Published
2026-01-26
Exploitation
Observed in the wild (CISA KEV)

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2025-52691

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2025-52691coverage & exploitation statusNVD · CVE.org

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