What’s Vulnerable › Vulnerabilities

CVE-2026-25067: SmarterTools SmarterMail < Build 9518 Unauthenticated background-of-the-day Path Coercion

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-01-29 · updated 2026-06-17
• Weakness: CWE-706

Description

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

How to fix

Upgrade to a fixed version: SmarterTools SmarterMail 100.0.9518. Check the vendor advisory for mitigations.

References

• https://www.smartertools.com/smartermail/release-notes/current
• https://www.vulncheck.com/advisories/smartertools-smartermail-unauthenticated-background-of-the-day-path-coercion

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