Unauthenticated credential coercion via unvalidated UNC path
Published Jan 29, 2026 · Updated Jan 29, 2026
Path coercion in SmarterTools SmarterMail before 100.0.9518 allows remote attackers to trigger outbound SMB authentication on Windows. The background-of-the-day preview endpoint base64-decodes attacker-controlled input and uses the result as an unvalidated filesystem path, allowing a UNC path to resolve to an attacker-controlled host. No authentication or user interaction is required; affected Windows services can disclose NTLM authentication material or support relay-based network authentication.
Summary
What happened
Path coercion in SmarterTools SmarterMail before 100.0.9518 allows remote attackers to trigger outbound SMB authentication on Windows. The background-of-the-day preview endpoint base64-decodes attacker-controlled input and uses the result as an unvalidated filesystem path, allowing a UNC path to resolve to an attacker-controlled host. No authentication or user interaction is required; affected Windows services can disclose NTLM authentication material or support relay-based network authentication.
The record
- CVE
- CVE-2026-25067
- Published
- Jan 29, 2026
- Updated
- Jan 29, 2026
- Vendor
- SmarterTools Inc.
- Product
- SmarterMail
- Classifications
- CWE-706, T1187
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 29, 2026CVE publishedPublication date reported by the CVE source.
- Jan 29, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=0 <100.0.9518
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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