CVE-2025-52691: in the CISA KEV catalogue

SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type Vulnerability. CISA added CVE-2025-52691 to the Known Exploited Vulnerabilities catalogue on 2026-01-26 with a default due date of 2026-02-16. Known ransomware campaign use: Known. Forensic triage flag: No.

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. (CISA description)

Vendor / product: SmarterTools SmarterMail
CWE: CWE-434
CISA 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.
EPSS: 86%, percentile 99 (scored 2026-11-03)

EPSS puts about 86 in 100 odds (86%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 99% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.

Vendor and reference links (from CISA)

Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.

Data dates. CISA KEV catalogue version 2026.11.03, released 2026-11-03, 1,767 entries (checked 2026-11-03). EPSS model v2026.06.15, scored 2026-11-03, 399,388 CVEs. Sources: CISA and FIRST (EPSS by FIRST; scores generated by Empirical Security). Copied to our own database and refreshed automatically; if a refresh fails, the previous copy keeps serving with its own date.

Frequently asked questions

Is CVE-2025-52691 in the CISA KEV catalogue?

Yes. CISA added CVE-2025-52691 (SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2026-01-26. CISA's default due date for it is 2026-02-16.

Is CVE-2025-52691 used in ransomware attacks?

CISA marks known ransomware campaign use as Known for CVE-2025-52691.

What should I do about CVE-2025-52691?

CISA's 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.

Sources

CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
NVD record for CVE-2025-52691