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Exploited vulnerability · CISA KEV

Is CVE-2026-24423 exploited? Yes: in CISA KEV since 5 Feb 2026

Gociux · SmarterTools SmarterMail · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2026-24423, SmarterTools SmarterMail Missing Authentication for Critical Function Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 5 Feb 2026, 13 days after it was published. It is known to be used in ransomware campaigns. It affects SmarterTools SmarterMail. If you run it, CISA's required action 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.

exploitedYesCISA KEV · 5 Feb 2026
ransomwareKnownused in campaigns
EPSStop 1%among the most likely CVEs to be exploited
severity9.3CVSS 4.0 · critical
US federal due26 Feb 2026BOD 22-01 deadline

What it 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.

VendorSmarterTools (3 exploited CVEs in KEV)
ProductSmarterMail
VulnerabilitySmarterTools SmarterMail Missing Authentication for Critical Function Vulnerability
WeaknessCWE-306
Published23 Jan 2026
Added to KEV5 Feb 2026
Reported by (CNA)VulnCheck

What to do

  1. Check whether you run it. Look for SmarterMail in your asset inventory, including appliances and cloud images. Stack check lists every exploited SmarterTools CVE at once.
  2. Apply the fix. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 23 Jan 2026.
  4. Get told next time. Email alerts when CISA adds a CVE for SmarterTools.

Other exploited CVEs in SmarterMail

References

Questions

Is CVE-2026-24423 being exploited?

Yes. CISA added CVE-2026-24423 to the Known Exploited Vulnerabilities catalog on 5 Feb 2026, which means there is reliable evidence of exploitation in the wild.

Is CVE-2026-24423 used in ransomware attacks?

Yes, CISA lists it as known to be used in ransomware campaigns.

How do I fix CVE-2026-24423?

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Check SmarterTools's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected SmarterMail and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in February 2026 · SmarterTools scorecard · act-now radar.

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