CVE entry · CVE-2026-24423
CVE-2026-24423: SmarterTools SmarterMail Missing Authentication for Critical Function Vulnerability
SmarterTools SmarterMail contains a missing authentication for critical function vulnerability in the ConnectToHub API method. This could allow the attacker to point the SmarterMail instance to a malicious HTTP server which serves the malicious OS command and could lead to command execution.
- Actively exploited: added to CISA’s KEV catalog on February 5, 2026.
- Used by ransomware, according to CISA.
- Remediation deadline for US federal agencies: February 26, 2026.
Description from CISA’s KEV catalog.
What to do
- Check whether your estate includes SmarterTools SmarterMail, including internet-facing devices.
- Apply the vendor’s patch or mitigations (references below). Failing that, isolate the product or stop using it, as CISA requires of US federal agencies.
- An exploited vulnerability has often been used before it was fixed: look for signs of compromise, especially on internet-facing devices.
References
- Vendor advisory or reference cited by CISA (www.smartertools.com)
- Vendor advisory or reference cited by CISA (www.cve.org)
- NVD entry (NIST)
- CISA KEV catalog