CVE-2026-24423: SmarterTools SmarterMail Missing Authentication for Critical Function Vulnerability

In short

SmarterTools SmarterMail has a weakness classified as missing authentication for critical function (CWE-306). CISA added it to its Known Exploited Vulnerabilities catalog on 2026-02-05. NVD lists CVSS 4.0 at 9.3 CRITICAL. CISA reports known ransomware campaign use.

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.” — CISA KEV, retrieved 2026-11-01

“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.” — NVD, retrieved 2026-11-01

Who is affected

SmarterTools SmarterMail. NVD lists the following versions as affected:

• Versions before 100.0.9511

Exploitation status

CISA KEV added: 2026-02-05. Known ransomware campaign use: Known (reported by CISA). Due date CISA set for US federal civilian agencies: 2026-02-26.

Scores

NVD CVSS 4.0: 9.3 CRITICAL; vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source [email protected].

EPSS by FIRST: 88.18%; percentile 99.77; score date 2026-10-31. EPSS estimates the probability of exploitation in the next 30 days.

CWE: CWE-306.

Timeline

CISA required action

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

What to do

• Confirm whether you run SmarterTools SmarterMail and which version.
• Apply the vendor update or mitigation in the vendor advisory.
• Follow CISA’s required action.
• Review the vendor guidance on signs of compromise.
• Track the fix through completion.

References

• Third Party Advisory: https://code-white.com/public-vulnerability-list/#systemadminsettingscontrollerconnecttohub-missing-authentication-in-smartermail
• Release Notes: https://www.smartertools.com/smartermail/release-notes/current
• Third Party Advisory: https://www.vulncheck.com/advisories/smartertools-smartermail-unauthenticated-rce-via-connecttohub-api
• NVD detail
• CVE.org record
• CISA KEV catalog

Sources and dates

CISA Known Exploited Vulnerabilities Catalog, version 2026.10.30; retrieved 2026-11-01. CISA KEV data: CC0 1.0. No endorsement by CISA.

NVD retrieved: 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

EPSS scores by FIRST; score date 2026-10-31.