Unauthenticated Remote Code Execution Vulnerability in SmarterMail by SmarterTools
CVE-2026-24423

9.3CRITICAL

Key Information:

Vendor

Smartertools

Status
Smartermail
Vendor
CVE Published:
23 January 2026

Badges

📈 Score: 116💰 Ransomware👾 Exploit Exists🟡 Public PoC🟣 EPSS 29%🦅 CISA Reported

What is CVE-2026-24423?

CVE-2026-24423 is a critical vulnerability that affects SmarterMail, an email server software produced by SmarterTools. This software is commonly deployed by organizations for managing email communications, providing features such as webmail access, spam filtering, and collaboration tools. The vulnerability specifically relates to the ConnectToHub API within SmarterMail versions prior to build 9511, allowing unauthenticated remote code execution. This means that an attacker can exploit this vulnerability to execute arbitrary commands on the server without any prior authentication, potentially compromising sensitive data and disrupting the operations of the affected organization. By leveraging this flaw, attackers can redirect the SmarterMail instance to a malicious HTTP server, which serves a harmful OS command to execute.

Potential impact of CVE-2026-24423

  1. Unauthorized Access and Control: The most significant impact is that attackers can gain unauthorized access to the server, enabling them to execute arbitrary code. This can lead to full control over the affected system, allowing for further exploitation or data exfiltration.

  2. Data Breach Risks: Organizations may face severe data breach incidents due to the attacker’s ability to manipulate or retrieve sensitive information stored within the SmarterMail environment, including email communications and attachments.

  3. Operational Disruption: The exploitation of this vulnerability could lead to operational disruptions, impacting email services and communication workflows within an organization. This can have cascading effects on business productivity and reputation.

CISA has reported CVE-2026-24423

CISA provides regional cyber and physical services to support security and resilience across the United States. CISA monitor the most dangerious vulnerabilities and have identifed CVE-2026-24423 as being exploited and is known by the CISA as enabling ransomware campaigns.

The CISA's recommendation is: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

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Affected Version(s)

SmarterMail 0 < 100.0.9511

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-24423
Created by aavamin

References

https://www.smartertools.com/smartermail/release-notes/cu...
release-notespatch
https://code-white.com/public-vulnerability-list/#systema...
third-party-advisory
https://www.vulncheck.com/advisories/smartertools-smarter...
third-party-advisory

EPSS Score

29% chance of being exploited in the next 30 days.

CVSS V4

Score:
9.3
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 💰

    Used in Ransomware

  • 🦅

    CISA Reported

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Sina Kheirkhah & Piotr Bazydlo of watchTowr
Markus Wulftange of CODE WHITE GmbH
Cale Black of VulnCheck
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