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CVE-2026-24423

Critical CVSS 9.8 Known exploited

Published 2026-01-23 · last changed 2026-08-04 · added to CISA KEV 2026-02-05

This one is being exploited in the wild.

CISA added CVE-2026-24423 to the Known Exploited Vulnerabilities catalog on 2026-02-05. Federal agencies are required to remediate it on a deadline. If you have affected machines, this is the class of finding that moves ahead of the rest of the queue.

The fix

We hold no Microsoft remediation data for CVE-2026-24423, which normally means it is not a Windows CVE. For non-Microsoft software the fix is the vendor's own updated release, and the affected versions are listed below.

What it is

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.

Sources

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H