KEV Intelligence

Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2025-52691

Upload Arbitrary Files

SmarterTools / SmarterMail · SmarterMail versions Build 9406 and earlier

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Severity
CVSS 10.0 · Critical
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
85.5%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2025-52691 is an unauthenticated Upload Arbitrary Files affecting SmarterTools SmarterMail. Successful exploitation of the vulnerability could allow an unauthenticated attacker to upload arbitrary files to any...

Is it exploited?

Yes. KEV Intelligence tracks this CVE as a known exploited vulnerability. Confidence is confirmed.

Who is affected?

SmarterTools / SmarterMail smartermail versions build 9406 and earlier.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

Upload Arbitrary Files

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.

Vendor Product Affected Status
SmarterTools SmarterMail SmarterMail versions Build 9406 and earlier Affected
Published
29 Dec 2025
Exploitation Reported
01 Jun 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

cisa nuclei_scanner malware

CVE References

Exploitation evidence

Why KEV Intelligence marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CVE

Recorded 01 Jun 2026

Independent exploitation attestation added to the KEV Intelligence record.

Used in malware

CVE

Recorded 02 Jun 2026

Malware families have been linked to exploitation of this CVE.

Proof of concept available

Nuclei Templates

Recorded 12 Jun 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the KEV Intelligence Pro API.

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Source Added
CVE First 2026-06-01 10:49 UTC
CISA 2026-06-02 14:03 UTC
Daily CyberSecurity 2026-06-08 02:20 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
0
User-Agents
0

Raw values available in Pro and Enterprise.

Virtual patch status

No KEV Intelligence virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2025/CVE-2025-52691.yaml 01 Jun 2026

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

10.0 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS

85.5%

Weaknesses

Unrestricted Upload of File with Dangerous Type CWE-434

Recent mention · Daily CyberSecurity

Collibra Platform Agent Flaws Allow Remote Code Execution Without Authentication

Privileged REST Endpoints and Zip Slip Vulnerability Threaten Data Clusters A threat notice has been issued for corporate The post Collibra Platform Agent Flaws Allow Remote Code Execution Without Authentication appeared first on Daily CyberSecurity. Related posts: Critical...

Read full advisory

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

SmarterMail - Unrestricted File Upload

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. Public PoC available

    Public proof-of-concept code published

  2. KEV confirmed by Daily CyberSecurity

    Exploitation attested by an external source

  3. First public exploitation report

    Exploit observed in malware

  4. Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  5. Nuclei template available

    Scanner coverage available

  6. Added to KEV Intelligence KEV Feed

    High-confidence, third-party attested exploitation

  7. CVE published

    Vulnerability disclosed publicly

  8. CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2025-52691

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2025-52691",
  "confidence": "Confirmed",
  "cvss_score": 10.0,
  "cvss_estimated": false,
  "epss_score": 0.85457,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

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