Known exploited · SmarterTools
CVE-2026-24423: SmarterTools SmarterMail Missing Authentication for Critical Function Vulnerability
What it is
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.
- Vendor
- SmarterTools
- Product
- SmarterMail
- Added to KEV
- February 5, 2026
- CISA due date
- February 26, 2026
- Ransomware use
- Known
What CISA requires
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Forensic triage
No
What to do now
- Find every instance of SmarterMail you run, including the forgotten ones, and check its version against the vendor advisory.
- Apply the vendor's fix or mitigation, before February 26, 2026 if you are bound by CISA's deadline, sooner if it faces the internet.
- Assume it was tried against you already: look for signs of exploitation from the date it was added, not from the day you patched.
References
H2 Security
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Start freeSource: CISA Known Exploited Vulnerabilities Catalog (public domain), catalog version 2026.10.01.