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CVE-2025-52691

SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type

10.0 CRITICALActively exploited (CISA KEV)Used in ransomwarePublic exploitEPSS 85.7%
  1. Published29 Dec 2025
  2. Added to CISA KEV26 Jan 2026
  3. Remediation due16 Feb 2026
Actively exploited (CISA KEV)

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.

Added to KEV: 26 Jan 2026Federal remediation due: 16 Feb 2026Used in ransomware

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 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeChanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected products

Smartertools Smartermail< 100.0.9413

Remediation

Fixed in
Smartertools Smartermail≥ 100.0.9413

References

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Frequently asked

Is CVE-2025-52691 being actively exploited?

Yes. CVE-2025-52691 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 26 Jan 2026. It has been used in ransomware campaigns.

How severe is CVE-2025-52691?

CVE-2025-52691 has a CVSS 3.1 base score of 10.0, rated critical. EPSS estimates a 85.7% probability of exploitation.

Which products are affected by CVE-2025-52691?

Affected products include Smartertools Smartermail.

How do I fix CVE-2025-52691?

Upgrade affected software to a fixed version, for example Smartertools Smartermail 100.0.9413 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2025-52691 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.