Exploited vulnerability · CISA KEV

Is CVE-2025-52691 exploited? Yes: in CISA KEV since 26 Jan 2026

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

Yes. CVE-2025-52691, SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 26 Jan 2026, 28 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.

What it is

SmarterTools SmarterMail contains an unrestricted upload of file with dangerous type vulnerability that could allow an unauthenticated attacker to upload arbitrary files to any location on the mail server, potentially enabling remote code execution.

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 29 Dec 2025.
4. Get told next time. Email alerts when CISA adds a CVE for SmarterTools.

Other exploited CVEs in SmarterMail

• CVE-2026-24423: SmarterTools SmarterMail Missing Authentication for Critical Function Vulnerability (5 Feb 2026)
• CVE-2026-23760: SmarterTools SmarterMail Authentication Bypass Using an Alternate Path or Channel Vulnerability (26 Jan 2026)

References

• www.smartertools.com/smartermail/release-notes/current
• www.csa.gov.sg/alerts-and-advisories/alerts/al-2025-124/
• nvd.nist.gov/vuln/detail/CVE-2025-52691

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 January 2026 · SmarterTools scorecard · act-now radar.