What is CVE-2026-24423?

CVE-2026-24423 is a critical-severity vulnerability in Smartertools Smartermail, classified under Missing Authentication for Critical Function. CVSS score: 9.8/10. Published 2026-01-23.

How severe is CVE-2026-24423?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2026-24423 known to be exploited?

Yes. CVE-2026-24423 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-02-05), indicating it is being actively exploited. 3 public proof-of-concept repositories are indexed.

Auth bypass in Smartertools Smartermail

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.

Vulnerability class: Broken Authentication

Published 2026-01-23 · last modified 2026-08-04.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.882 (99.8th percentile), scored 2026-10-19.

High probability of exploitation in the next 30 days — patch promptly. 100th percentile — 99.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.882 · newest: 0.882 · change: 0.000

Affected products

Smartertools Smartermail — versions 0

Weakness classification (CWE)

CWE-306 — Missing Authentication for Critical Function

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2026-02-05. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2026-02-26.

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.

Known ransomware campaign use: yes.

Public proof-of-concept exploits

References

www.smartertools.com/smartermail/release-notes/current (release-notes, Release Notes, patch)
code-white.com/public-vulnerability-list/ (Third Party Advisory, third-party-advisory)
www.vulncheck.com/advisories/smartertools-smartermail-unauthenticated-rce-via-c… (Third Party Advisory, third-party-advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2026-24423?: CVE-2026-24423 is a critical-severity vulnerability in Smartertools Smartermail, classified under Missing Authentication for Critical Function. CVSS score: 9.8/10. Published 2026-01-23.
How severe is CVE-2026-24423?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2026-24423 known to be exploited?: Yes. CVE-2026-24423 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-02-05), indicating it is being actively exploited. 3 public proof-of-concept repositories are indexed.