CVE-2025-52691
CriticalExploitedPublic exploitSuccessful exploitation of the vulnerability could allow an unauthenticated attacker to upload arbitrary files to any location on the mail server, potentially enabling remote code execution.
Published Dec 29, 2025 · Updated Oct 7, 2026
Key Facts
Patch immediately- CVE-2025-52691 is a critical-severity vulnerability (CVSS 10.0 v3.1) affecting SmarterMail (Smartertools).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jan 22, 2026 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 86% probability of exploitation in the next 30 days.
- Fixed versions are available, including SmarterMail 100.0.9413.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
10.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
86%
Higher than 99.7% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2025-52691 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
Successful exploitation of the vulnerability could allow an unauthenticated attacker to upload arbitrary files to any location on the mail server, potentially enabling remote code execution.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Jan 26, 2026 | Feb 16, 2026 | Known |
| Industry KEV feed | Jan 22, 2026 | Feb 16, 2026 | Known |
| CIRCL KEV | Jan 26, 2026 | Feb 16, 2026 | Not reported |
| ENISA EUVD | Jan 26, 2026 | n/a | Not reported |
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.
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| SmarterMailSmartertools | >= SmarterMail versions Build 9406 and earlier | 100.0.9413 |
Patched Releases
SmarterMail
100.0.9413
Timeline
Publicly disclosed
Dec 29, 2025
Added to Industry KEV feed
Jan 22, 2026
Added to CISA KEV
Jan 26, 2026
Added to CIRCL KEV
Jan 26, 2026
Added to ENISA EUVD
Jan 26, 2026
Last updated
Oct 7, 2026
Weakness Type
- CWE-434 Unrestricted Upload of File with Dangerous Type
References
- advisoryhttps://www.csa.gov.sg/alerts-and-advisories/alerts/al-2025-124/
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitMSF smartermail_guid_file_upload.rb
- exploithttps://github.com/watchtowrlabs/watchTowr-vs-SmarterMail-CVE-2025-52691?ref=labs.watchtowr.com
FAQ
Common Questions.
Successful exploitation of the vulnerability could allow an unauthenticated attacker to upload arbitrary files to any location on the mail server, potentially enabling remote code execution.
Affected: SmarterMail (Smartertools) versions >= SmarterMail versions Build 9406 and earlier. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jan 22, 2026 and is known to be used in ransomware campaigns.
Yes. It was added on Jan 26, 2026 with a federal remediation due date of Feb 16, 2026.
Public exploit code is available.
Fixed versions are available, including SmarterMail 100.0.9413.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
Is CVE-2025-52691 Running On Your Attack Surface?
Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.
Request A Demo