CVE-2026-24423
About
SmarterTools SmarterMail versions prior to build 9511 contain an unauthenticated remote code execution vulnerability in the ConnectToHub API method. The attacker could point the SmarterMail to the malicious HTTP server, which serves the malicious OS command. This command will be executed by the vulnerable application.
Rainforest analyst review
SmarterTools SmarterMail before build 9511 exposes an unauthenticated remote code execution flaw in the ConnectToHub API method. The method can be induced to contact an attacker-controlled HTTP server, which serves back a malicious operating-system command that the SmarterMail application then executes. Because the endpoint requires no authentication, an attacker only needs to reach the API and point it at their own server to run arbitrary commands on the mail host.
SmarterMail is a Windows mail server used by hosting providers and small-to-mid enterprises, so a compromised instance exposes email content, credentials, and the trusted position of a mail system that can be abused to send and intercept messages. Mail servers are internet-facing by necessity, which keeps this endpoint reachable and discoverable by scanners once details circulate. Upgrade to build 9511 or later promptly, restrict access to the management and API surface where the deployment allows, and given that the flaw lets the server be steered to fetch attacker-supplied commands, review affected hosts for unexpected outbound connections and command execution rather than relying solely on the update.
References
- https://code-white.com/public-vulnerability-list/#systemadminsettingscontrollerconnecttohub-missing-authentication-in-smartermail
- https://www.smartertools.com/smartermail/release-notes/current
- https://www.vulncheck.com/advisories/smartertools-smartermail-unauthenticated-rce-via-connecttohub-api
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-24423
Related CVEs
Frequently asked questions
What is CVE-2026-24423?
SmarterTools SmarterMail versions prior to build 9511 contain an unauthenticated remote code execution vulnerability in the ConnectToHub API method. The attacker could point the SmarterMail to the malicious HTTP server, which serves the malicious OS command. This command will be executed by the vulnerable application.
How severe is CVE-2026-24423?
CVE-2026-24423 carries a CVSS 3.1 base score of 9.8, rated critical. On the Rainforest Risk Index — which weighs the severity alongside how easy the flaw is to reach and how broad its impact is — it scores 99 out of 100, in the critical band.
How is CVE-2026-24423 exploited?
According to the CVSS vector (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H): attack vector Network, attack complexity Low, privileges required None, user interaction None. Impact on confidentiality High, integrity High and availability High.
Which products are affected by CVE-2026-24423?
Public advisories list the following as affected: smartermail. Check the references on this page for the exact versions each vendor confirms.
How do I fix CVE-2026-24423?
Apply the fix the vendor published — the references on this page link to the primary advisories and patches. When patching can't happen right away, reduce the exposure of the affected component and watch it for exploitation attempts. Rainforest customers see this vulnerability correlated to their own assets and prioritized by real exposure, not by score alone.
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