CVE-2025-52691
Published: January 26, 2026
Official Description
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 KEV Advisory
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.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Risk Analysis
SmarterTools SmarterMail is affected by a critical unrestricted file upload vulnerability, allowing an unauthenticated attacker to upload arbitrary files to any location on the mail server. This could lead to remote code execution, granting full control over the server. The CVSS score of 10.0 and high EPSS score of 0.78375 indicate a critical and highly likely to be exploited flaw, further confirmed by its presence in CISA's KEV.
This vulnerability is actively exploited in the wild, as confirmed by its presence in CISA's KEV. It is remotely exploitable by an unauthenticated attacker.
Immediately apply all available patches and updates for SmarterTools SmarterMail. Implement robust input validation for file uploads and restrict write access to critical directories.
Technical Analysis
CVE-2025-52691 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 10.0.
The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.
CISA has added CVE-2025-52691 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
CVSS v3.1 Vector Breakdown
Exploit & PoC Resources
All References (3)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2025-52691 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1