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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 16 Feb 2026. Known ransomware use
SmartermailApplication · Smartertools

CVE-2025-52691

CRITICAL · 10.0 CVSS v3.1 Published 2025-12-29
Fix available
A fix is available. Upgrade to 100.0.9413 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Ransomware High EPSS Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

This is an unauthenticated arbitrary file upload vulnerability in a mail server product. An attacker can upload files to any location on the server, which can then be leveraged to achieve remote code execution.

MitigationApply the vendor's latest security patch for the affected mail server product immediately. Restrict file upload functionality and review server configuration while awaiting the patch.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
SmartermailApplication
Affected:< 100.0.9413

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Smartermail version
    Access the Smartermail web admin interface (commonly on port 9998 or 443) and navigate to the About or System Information page. Alternatively, check the installed software list on the server for Smartermail version information.
    Affected if The installed version is below 100.0.9413
  2. Verify unauthenticated access is enabled
    In the Smartermail admin interface, check Settings > Security or Settings > Access to see if unauthenticated/anonymous access is permitted for email receiving or the webmail service.
    Affected if Unauthenticated access is enabled and the server accepts connections from untrusted networks
  3. Confirm network exposure of the mail server
    Determine if the Smartermail web interface (ports 80, 443, or custom ports like 9998) is reachable from external/untrusted IP addresses by reviewing firewall rules, NAT configurations, or performing a port scan from outside the internal network.
    Affected if The mail server web services are exposed to the internet or untrusted networks without IP-based access restrictions
  4. Check for abnormal file creation
    Review the Smartermail service directory (typically located in the installation folder, often under C:\Program Files\SmarterTools\SmarterMail or /opt/smartermail/) for unexpected files or scripts in system directories outside the normal mail storage paths.
    Affected if Unexpected files appear in system directories or the Smartermail service can write to locations outside its designated mail storage area

You are affected if running Smartermail version below 100.0.9413 with unauthenticated access enabled and the server is network-accessible from untrusted sources.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 100.0.9413 or later
Fixed in 100.0.9413
Interim mitigation

Apply the vendor's latest security patch for the affected mail server product immediately. Restrict file upload functionality and review server configuration while awaiting the patch.

Recommended fix High confidence

Smartermail version 100.0.9413 or later

  1. 1. Ensure you have a complete backup of your Smartermail installation, including the mail data directory and configuration files.
  2. 2. Download the latest Smartermail build (100.0.9413 or later) from the official Smartermail download page or your licensed customer portal.
  3. 3. Stop the Smartermail service before applying the update.
  4. 4. Run the installer or apply the update package to upgrade the Smartermail installation.
  5. 5. After upgrade completes, verify the service starts successfully.
  6. 6. Test mail flow functionality to ensure the upgrade did not disrupt normal operations.
  7. 7. Verify the Smartermail version shows 100.0.9413 or higher in the admin interface.
Caveat Review Smartermail release notes for version 100.0.9413 for any configuration or feature changes that may affect your deployment

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Smartermail Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,560
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,096.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-52691 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data