Known exploited vulnerability
CVE-2025-52691
The short answer
CVE-2025-52691 affects SmarterTools SmarterMail and is rated critical (CVSS 10.0). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-01-26: attackers are using it, so patch it first.
What it is
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.
Weakness: CWE-434.
Severity
10.0 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Exploited (CISA KEV)
Yes, since Jan 26, 2026
Federal due date Feb 16, 2026
EPSS, next 30 days
86%
Higher than 100% of scored CVEs
How it can be exploited
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
What CISA says to do
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
SmarterMail. NVD's record lists the exact affected versions.
References
- www.csa.gov.sg/alerts-and-advisories/alerts/al-2025-124/ Third Party Advisory
- github.com/watchtowrlabs/watchTowr-vs-SmarterMail-CVE-2025-52691?ref=labs.watchtowr.com ExploitThird Party Advisory
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-52691 US Government Resource
Questions
Is CVE-2025-52691 being exploited?
Yes. CISA added CVE-2025-52691 to its Known Exploited Vulnerabilities catalog on 2026-01-26, with a federal remediation due date of 2026-02-16. CISA lists it as used in ransomware campaigns.
How do I fix 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.
From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.
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