CVE-2026-24423

SmarterTools SmarterMail < Build 9511 Unauthenticated RCE via ConnectToHub API

Exploited in attacks Used by ransomware Critical 9.3 Attack chance: 88%

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.

CISA: 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.

What to do

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Deadline for US federal agencies: February 26, 2026

smartertools.com/smartermail/release-notes/current

Added to the CISA list: February 5, 2026
Published: January 23, 2026
Severity: Critical 9.3 CVSS 4.0
Chance of attacks in the next 30 days (EPSS): 88% in the top 0.2% of all known vulnerabilities
Weakness: CWE-306
More details: NVD · CVE.org · CISA

All references (3)

More exploited flaws from SmarterTools

Added	Vulnerability	Product	Severity	Attack chance
Jan 26, 2026	Unrestricted Upload of File with Dangerous TypeCVE-2025-52691used by ransomware	SmarterMail	Critical 10.0	86%
Jan 26, 2026	Authentication Bypass Using an Alternate Path or ChannelCVE-2026-23760used by ransomware	SmarterMail	Critical 9.3	96%

All of them →

Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.