---
title: "CVE-2025-52691: SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type Vulnerability"
url: https://erroneo.us/security/cve/CVE-2025-52691/
description: "CVE-2025-52691 (SmarterTools SmarterMail): Exploited in the wild (CISA KEV). Successful exploitation of the vulnerability could allow an unauthenticated…"
type: vulnerability-record
section: "Security Digest"
date_published: 2025-12-29
date_modified: 2026-02-26
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2025-52691"
kev: true
cvss: 10
epss: 0.85655
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run SmarterTools SmarterMail. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-01-26, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-02-16 ; treat that as the outer limit, not the target. CISA also lists it as known to be used in ransomware campaigns .
- EPSS 85.7% , percentile 99.7: FIRST’s model estimates a 85.7% chance of exploitation activity in the next 30 days, higher than 99.7% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.

## What it is

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.

## Affected products (CVE record)

- SmarterTools SmarterMail: SmarterMail versions Build 9406 and earlier

## Severity

- CSA CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: added 2026-01-26; federal due date 2026-02-16. Known ransomware use: Known.
- CISA 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.
- CISA SSVC assessment: exploitation active , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 85.66% probability of exploitation activity in the next 30 days; percentile 99.7.

## Sources

- [Listed in CISA KEV notes (smartertools.com)](https://www.smartertools.com/smartermail/release-notes/current)
- [Listed in CISA KEV notes (csa.gov.sg)](https://www.csa.gov.sg/alerts-and-advisories/alerts/al-2025-124/)
- [CVE.org record CVE-2025-52691](https://www.cve.org/CVERecord?id=CVE-2025-52691)
- [NVD entry CVE-2025-52691](https://nvd.nist.gov/vuln/detail/CVE-2025-52691)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-52691)
- [github.com](https://github.com/watchtowrlabs/watchTowr-vs-SmarterMail-CVE-2025-52691?ref=labs.watchtowr.com)

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Source page: https://erroneo.us/security/cve/CVE-2025-52691/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt