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CVE-2025-52691

10, critical Known exploited Used in ransomware

SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab) CISA KEV catalogue (opens in a new tab)
CVSS
10, critical critical CVSS v3.1
EPSS, next 30 days
86% higher than 99.7% of scored CVEs
Exploitation
Confirmed in the wild
Published
29 Dec 20259 months ago

Known exploited

CISA added this to the Known Exploited Vulnerabilities Catalog on 26 Jan 2026 and links it to ransomware activity. US federal agencies had to remediate by 16 Feb 2026, a deadline that has passed.

Required action. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

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.

Details

Vendor
SmarterTools
Product
SmarterMail
Weakness
CWE-434 (opens in a new tab)
Status
Analyzed
Updated
7 Oct 2026
Assigner
5f57b9bf-260d-4433-bf07-b6a79e9bb7d4

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

References 3

Exploit code 1

Advisories 1

Other references 1

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other SmarterTools CVEs

Every SmarterTools CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-24423 SmarterTools SmarterMail Missing Authentication for Critical Function Vulnerability KEV EPSS 88% 9.8, critical
  • CVE-2026-23760 SmarterTools SmarterMail Authentication Bypass Using an Alternate Path or Channel Vulnerability KEV EPSS 97% 9.8, critical
  • CVE-2026-104082 Smartertools Smartermail Code Injection Vulnerability EPSS 0.6% 7.2, high

Beyond this page

Is CVE-2025-52691 in your network?

This page tells you how dangerous CVE-2025-52691 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

CVE-2025-52691 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.

  • EXYS7600 OCELOT

    Find it before attackers do

    Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2025-52691 comes with the devices to patch.

    Learn more about EXYS7600 OCELOT

  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

    Learn more about EXYS7950 KONDRA
Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.