Threat Intelligence / CVE / CVE-2026-24423

CVE-2026-24423 — Smartertools Smartermail

CISA KEVRansomware
CVSS v3.1 9.8 (CRITICAL) · CVSS v4.0 9.3 · EPSS 66.4% (higher than 98.5% of all scored CVEs) · Priority 10/10 · Published 2026-01-23

As of 2026-02-06, CVE-2026-24423 is a CRITICAL-severity vulnerability in Smartertools Smartermail, CVSS v3.1 9.8, EPSS 66.4% (98.5th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-02-05), with a US federal remediation deadline of 2026-02-26, and CISA links it to known ransomware campaigns. Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-24423, most recently “SmarterMail Dual-CVE Pre-Auth RCE Chain — CVE-2026-23760 Admin Password Reset + CVE-2026-24423 ConnectToHub RCE, CISA KEV, Mass Automated Exploitation, 2-Day Patch Weaponization via .NET Decompiler”.

Last updated: 2026-02-06

What is CVE-2026-24423?

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 record classifies CVE-2026-24423 under weakness class CWE-306. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 233 days ago.

Severity and exploitation probability

CVSS v3.1 base score
9.8 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0 base score
9.3
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
EPSS (FIRST)
66.4% probability of exploitation in the next 30 days, higher than 98.5% of all scored CVEs
CISA KEV
Listed since 2026-02-05, federal remediation deadline 2026-02-26 — used in known ransomware campaigns
Threadlinqs priority
10/10 — CISA lists it as used in ransomware, which Threadlinqs scores at the maximum
Published
2026-01-23, last modified 2026-02-06

Is CVE-2026-24423 being exploited?

CISA added CVE-2026-24423 to the Known Exploited Vulnerabilities catalog on 2026-02-05, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2026-02-26 under BOD 22-01. CISA flags the vulnerability as one used in known ransomware campaigns. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.

Affected products and versions

How to fix CVE-2026-24423

Because CVE-2026-24423 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2026-02-26. No vendor patch reference has been recorded for CVE-2026-24423 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

Threat activity tracking CVE-2026-24423

1 tracked threat in the Threadlinqs corpus references CVE-2026-24423, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2026-24423 are available via the Threadlinqs MCP server (Purple tier). View plans →

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