CVE-2026-25067: SmarterTools SmarterMail

Medium severity, CVSS 5.3. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• SmarterTools SmarterMail: before 100.0.9518 (fixed in 100.0.9518)

Published 2026-01-29. Last modified 2026-06-17.