Threats / SmarterTools / CVE-2025-52691
CVE-2025-52691
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-07
SmarterTools SmarterMail vulnerability
SmarterMail contains an unrestricted file upload vulnerability allowing unauthenticated attackers to upload arbitrary files, potentially enabling remote code execution on mail servers.
Verdict
Today item, not a backlog item.
An unauthenticated attacker can exploit CWE-434 to upload malicious files without restriction, achieving code execution on affected SmarterMail instances. Active exploitation and ransomware campaigns confirm critical risk.
01
Is it exploitable?
— the evidence, ranked above the scoreExploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-01-26), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.8966 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: SmarterTools, SmarterMail. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-434 Unrestricted File Upload — weakness family: Path traversal / file.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No threat-actor attribution is established from the public feed for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a malicious file and send an HTTP request to the vulnerable upload endpoint without authentication.
Business
The organization's mail server is immediately accessible to external threat actors without credential requirements.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I upload a web shell or executable to an arbitrary location on the server filesystem.
Business
Attackers gain persistent code execution capability within the mail infrastructure.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute commands on the compromised server to establish lateral movement and data exfiltration.
Business
Email data, user credentials, and sensitive communications are exposed to theft and manipulation.
4
Data at risk — exfiltration narrative 4
Attacker
I deploy ransomware payloads across the mail server and connected systems.
Business
Critical business operations halt; ransom demands follow with threat of data publication.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05
Coverage & confidence
— what we know, and what we don’tEstablished (cited)
Coverage gaps — stated, not hidden
Disclosure & credit2
Catalogued by CSACNA
Credited with finding itChua Meng Hanfinder