What is the CVSS score of CVE-2026-24423?

CVE-2026-24423 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 29.3%.

Which versions of Smartermail are affected by CVE-2026-24423?

SmarterMail servers are vulnerable to unauthenticated remote code execution attacks that are actively being exploited in the wild.

Is there a public PoC exploit available for CVE-2026-24423?

Yes, a public proof-of-concept exploit is available for CVE-2026-24423. Prioritise patching immediately. EPSS: 29.3%.

How to fix or mitigate CVE-2026-24423?

Within 24 hours: Identify all SmarterMail instances and versions in your environment; isolate affected systems from untrusted networks if possible. Within 7 days: Implement network-level controls (WAF rules, IP whitelisting) to restrict ConnectToHub API access; monitor logs for exploitation attempts. Within 30 days: Contact SmarterTools for patch availability and timeline; plan emergency patching upon release; consider alternative email solutions if patch is delayed beyond 30 days.

Smartermail CVE-2026-24423

CRITICAL

Missing Authentication for Critical Function (CWE-306)

2026-01-23 disclosure@vulncheck.com

RCE Command Injection Smartermail

9.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

9.8 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:54 vuln.today

Added to CISA KEV

Feb 06, 2026 - 16:45 cisa

CISA KEV

CVE Published

Jan 23, 2026 - 17:16 nvd

CRITICAL 9.8

DescriptionCVE.org

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.

AnalysisAI

SmarterTools SmarterMail prior to build 9511 contains a second critical vulnerability (CVE-2026-24423) — an unauthenticated remote code execution flaw in the ConnectToHub API method. An attacker can redirect the SmarterMail server to connect to a malicious HTTP endpoint that serves OS commands for execution. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access

Send crafted request to ConnectToHub API

Exploit

Point SmarterMail to malicious HTTP server

Impact

Execute attacker-controlled OS command as application user

Access

Send crafted request to ConnectToHub API

Exploit

Point SmarterMail to malicious HTTP server

Impact

Execute attacker-controlled OS command as application user

Vulnerability AssessmentAI

Exploitation	SmarterMail versions prior to build 9511 with ConnectToHub API endpoint exposed. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment	CVSS 9.8 (Critical). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario	An attacker sets up a malicious HTTP server that mimics the SmarterMail hub protocol. They send an unauthenticated request to the target's ConnectToHub API with the URL of their malicious server. …
Remediation	Upgrade SmarterMail to build 9511 or later immediately. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours: Identify all SmarterMail instances and versions in your environment; isolate affected systems from untrusted networks if possible. …

Threat intelligence, references, and detailed analysis are available after sign-in.

CVE-2026-24423 vulnerability details – vuln.today

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Smartermail CVE-2026-24423

Severity by source

CVSS VectorNVD

Lifecycle Timeline

DescriptionCVE.org

AnalysisAI

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Attack ChainAIDerived

Vulnerability AssessmentAI

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External POC / Exploit Code