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SmartermailApplication · Smartertools

CVE-2026-25067

MEDIUM · 5.3 CVSS v3.1 Published 2026-01-29
Fix available
A fix is available. Upgrade to 100.0.9518 or later.
See remediation →
62/100
Remediation priority · Elevated
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
SmarterTools SmarterMail versions prior to build 9518 contain an unauthenticated path coercion vulnerability in the background-of-the-day preview endpoint. The application base64-decodes attacker-supplied input and uses it as a filesystem path without validation. On Windows systems, this allows UNC paths to be resolved, causing the SmarterMail service to initiate outbound SMB authentication attempts to attacker-controlled hosts. This can be abused for credential coercion, NTLM relay attacks, and unauthorized network authentication.

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 · high confidence

SmarterMail's background-of-the-day preview endpoint accepts base64-encoded input, decodes it, and uses the result as a filesystem path without validation. This allows attackers to supply UNC paths (e.g., \\attacker\share) that cause the SmarterMail service account to authenticate to attacker-controlled SMB servers, enabling credential capture and NTLM relay attacks.

MitigationUpgrade to SmarterMail build 9518 or later, which includes input validation to prevent path coercion. Additionally, apply network segmentation and outbound firewall rules to block SMB (TCP 445) connections from the SmarterMail server to untrusted hosts.

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:< 100.0.9518

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
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

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

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 installation and version
    Locate SmarterMail installation directory and check version information (typically in About or System Info page, or check the installed binary version)
    Affected if Installed version is lower than 100.0.9518
  2. Confirm the background-of-the-day preview feature is accessible
    Verify the web interface is running and accessible - the vulnerability exists in the background-of-the-day preview endpoint
    Affected if The SmarterMail web interface with the background-of-the-day feature is exposed and reachable
  3. Review server logs for suspicious outbound SMB connections
    Examine SmarterMail and Windows event logs for SMB/TCP 445 connection attempts from the SmarterMail server to unexpected external IP addresses, particularly those not on your internal network
    Affected if Logs show outbound SMB connections initiated by the SmarterMail service account to unknown or external hosts
  4. Check for NTLM authentication attempts to untrusted hosts
    Enable and review NTLM auditing in Windows security logs - look for authentication events from the SmarterMail service account to unknown SMB servers
    Affected if The service account has attempted NTLM authentication to attacker-controlled or untrusted systems

A user is affected if they run SmarterMail with a build version below 100.0.9518 AND have the background-of-the-day preview endpoint accessible, particularly if outbound SMB connections to untrusted hosts are observed in logs.

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 100.0.9518 or later
Fixed in 100.0.9518
Interim mitigation

Upgrade to SmarterMail build 9518 or later, which includes input validation to prevent path coercion. Additionally, apply network segmentation and outbound firewall rules to block SMB (TCP 445) connections from the SmarterMail server to untrusted hosts.

Recommended fix High confidence

Smartermail build 9518 (version 100.0.9518)

  1. Ensure you have a current backup of your Smartermail installation and data
  2. Download Smartermail version 100.0.9518 or later from the official SmarterTools download page
  3. Stop the SmarterMail service before applying the upgrade
  4. Run the installer to upgrade to the fixed build
  5. After installation, verify the service starts successfully
  6. Confirm the background-of-the-day preview endpoint now properly validates input before use as a filesystem path

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

Fix this in Smartermail Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,680
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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-2026-25067 in production — separate from our analysis above.

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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