CVE-2026-24423

SmarterTools SmarterMail: Missing Authentication for Critical Function

As of , CVE-2026-24423 in SmarterTools SmarterMail is on CISA's list of exploited vulnerabilities: CISA listed it on . Our patch-first group: Patch now.

Exploited
Yes: CISA listed it on 5 February 2026
US federal deadline
26 February 202621 days after CISA listed it. US federal civilian agencies must fix it by then.
Used in ransomware campaigns
KnownCISA changed it from Unknown to Known on 5 February 2026.
EPSS score
0.88Higher than 99% of the CVEs EPSS scores. EPSS estimates the chance of exploitation activity in the next 30 days.
Public exploit
None foundNeither Metasploit nor Exploit-DB lists one.
Fix
Vendor advice: www.cve.org and www.smartertools.comLinks below, from CISA's entry.

What CISA says 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.

CISA's required action

What the flaw 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's description

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.

The CVE record's description, from VulnCheck

CVE published
23 January 2026
Assigned by
VulnCheck
CVSS
9.3 Critical (CVSS 4.0, from the CNA)
CWE-306
Missing Authentication for Critical Function
CISA SSVC, exploitation
active
CISA SSVC, automatable
yes
CISA SSVC, technical impact
total

Timeline

  1. The CVE record was published.
  2. CISA added it to its list of exploited vulnerabilities.
  3. CISA changed its entry. Ransomware use: Unknown to Known.
  4. The US federal deadline to fix it.

SmarterMail: other exploited entries

VulnerabilityProductOur groupListedDeadlineEPSS
CVE-2025-52691Unrestricted Upload of File with Dangerous TypeSmarterTools SmarterMailPatch nowRansomware use, listed within a year; Metasploit module0.86
CVE-2026-23760Authentication Bypass Using an Alternate Path or ChannelSmarterTools SmarterMailPatch nowRansomware use, listed within a year0.97

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