---
id: "CVE-2025-52691"
kind: "vulnerability"
aliases: ["CVE-2025-52691"]
title: "smartertools smartermail: Successful exploitation of the vulnerability could allow an unauthenticated attacker to upload arbitrary files to\u2026"
severity: "critical"
cvss: 10.0
epss: null
exploited: true
status: "open"
category: "vendor"
products: [{"name": "smartertools smartermail", "fixed": ["100.0.9413"], "affected": "< 100.0.9413", "ecosystem": "vendor"}, {"name": "SmarterTools SmarterMail", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["cloudflare", "exploited", "lab-disclosure", "mail-server", "ransomware", "self-hosted", "smartermail", "vendor"]
not_affected_if: ["managed-hosting"]
published_at: "2025-12-29T03:15:42+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-24T19:12:57+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2025-52691", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-52691", "first_seen_at": "2026-10-23T23:44:51+00:00"}, {"source": "lab", "url": "https://developers.cloudflare.com/changelog/post/2026-03-02-waf-release/", "first_seen_at": "2026-10-24T19:12:57+00:00"}]
---

# smartertools smartermail: Successful exploitation of the vulnerability could allow an unauthenticated attacker to upload arbitrary files to…

SmarterTools SmarterMail, a mail server product, has an unrestricted file upload flaw that lets an unauthenticated attacker write arbitrary files anywhere on the server. The sources say this can lead to remote code execution, and CISA lists it as actively exploited, including in ransomware campaigns.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:smartertools smartermail affected < 100.0.9413 fixed 100.0.9413
- vendor:SmarterTools SmarterMail affected ? fixed ?

## How to check

Check the installed SmarterMail version against the vendor advisory; the sources do not give a version or file path to inspect.

## Fix

Apply the mitigations from the SmarterTools vendor instructions, as CISA directs; the sources do not name a fixed version.
If no mitigation is available, discontinue use of the product as CISA advises.

## Mitigated for you by

- Cloudflare (waf-rule, since 2026-03-02): covers HTTP requests proxied through Cloudflare, matched by the Cloudflare Managed Ruleset rule 'SmarterMail - Arbitrary File Upload - CVE-2025-52691' (action changed from Log to Block) Limits: Only traffic proxied through Cloudflare; requests reaching the origin directly are not covered; none further stated Still: Apply the vendor patches for SmarterMail without delay; the rule is a detection layer, not a fix https://developers.cloudflare.com/changelog/post/2026-03-02-waf-release/

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2025-52691
- 2026-10-23T23:44:51+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2025-52691
- 2026-10-24T19:12:57+00:00 lab https://developers.cloudflare.com/changelog/post/2026-03-02-waf-release/ — Cloudflare: WAF Release - 2026-03-02 · Changelog

## Documents

- [advisory] Cloudflare: WAF Release - 2026-03-02 · Changelog https://developers.cloudflare.com/changelog/post/2026-03-02-waf-release/

## From the sources

WAF Release - 2026-03-02 · Changelog

# Changelog

New updates and improvements at Cloudflare.

March 2, 2026

## WAF Release - 2026-03-02

This week's release introduces new detections for vulnerabilities in SmarterTools SmarterMail (CVE-2025-52691 and CVE-2026-23760), alongside improvements to an existing Command Injection (nslookup) detection to enhance coverage.

Key Findings

- CVE-2025-52691: SmarterTools SmarterMail mail server is vulnerable to Arbitrary File Upload, allowing an unauthenticated attacker to upload files to any location on the mail server, potentially enabling remote code execution.
- CVE-2026-23760: SmarterTools SmarterMail versions prior to build 9511 contain an authentication bypass vulnerability in the password reset API permitting unaunthenticated to reset system administrator accounts failing to verify existing password or reset token.

Impact

Successful exploitation of these SmarterMail vulnerabilities could lead to full system compromise or unauthorized administrative access to mail servers. Administrators are strongly encouraged to apply vendor patches without delay.

| Ruleset | Rule ID | Legacy Rule ID | Description | Previous Action | New Action | Comments |
| --- | --- | --- | --- | --- | --- | --- |
| Cloudflare Managed Ruleset | ...966ec6b1 | N/A | SmarterMail - Arbitrary File Upload - CVE-2025-52691 | Log | Block | This is a new detection. |
| Cloudflare Managed Ruleset | ...ee964a8c | N/A | SmarterMail - Authentication Bypass - CVE-2026-23760 | Log | Block | This is a new detection. |
| Cloudflare Managed Ruleset | ...75b64d99 | N/A | Command Injection - Nslookup - Beta | Log | Block | This rule is merged into the original rule "Command Injection - Nslookup" (ID: ...b090ba9a) |

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_