CVE-2026-104082: SmarterMail before build 9777 contains a remote code execution vulnerability that allows an attacker holding a SysAdmin-scoped access token to bypass the Volume

SmarterMail before build 9777 contains a remote code execution vulnerability that allows an attacker holding a SysAdmin-scoped access token to bypass the Volume

SmarterMail before build 9777 contains a remote code execution vulnerability that allows an attacker holding a SysAdmin-scoped access token to bypass the Volume Mount script-directory containment control by provisioning a new mail domain with an arbitrary FileStore root path inside the trusted Scripts directory via the domain-put endpoint. Attackers can disclose the Scripts path through the AddOrUpdateMount endpoint, clear the upload extension blacklist via the global-mail endpoint, then upload a malicious script through the ordinary mail file-storage upload API so that saving a CommandMount triggers RunScript before validation, resulting in a reverse shell executing as the SmarterMail service account with SYSTEM-level privileges.

Description from the National Vulnerability Database, published by VulnCheck

What it means for a small business

If your business uses Smartermail, install the vendor's update. If you're not sure whether you use it, ask whoever manages your computers.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.87%, higher than 58% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 29, 2026, updated daily.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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