CVE-2025-52691
Confirmed PUBLISHEDUpload Arbitrary Files
1 day faster than CISA KEV
Recommended Action
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
At a Glance
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.
- CVE Published
- Dec 29, 2025
- Exploitation Reported
- Jun 01, 2026
- CVSS
- 10.0 Critical
- EPSS
- 85.5%
Affected Versions
| Vendor | Product | Version | Status |
|---|---|---|---|
| SmarterTools |
SmarterMail
|
SmarterMail versions Build 9406 and earlier |
Affected |
CVE References
- csa.gov.sg/alerts-and-advisories/alerts/al-2025-124 csa.gov.sg · CVE Record https://www.csa.gov.sg/alerts-and-advisories/alerts/al-2025-124/
Recommended Actions
- Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
- Check enrichment artifacts for scanner coverage and available PoCs before rolling remediation validation.
- Use the Pro API to automate enrichment, telemetry, and workflow delivery for VM, SOC, and CTI pipelines.
Known Exploited Vulnerability Sources
Catalogues that list this CVE as a known exploited vulnerability.
Per-source evidence links for KEV attestations are available through the KEVIntel Pro API.
Learn about Pro API access| 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 |
Scanner Artifacts
Nuclei and Metasploit references linked to this CVE.
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2025/CVE-2025-52691.yaml | Jun 01, 2026 |
Virtual Patch
Compensating WAF rules to help reduce exposure to this CVE. Rule content and deployable vendor exports are available with KEVIntel Enterprise.
KEVIntel does not currently have a virtual patch for this CVE. When available, KEVIntel virtual patches ship as deployable ModSecurity, Cloudflare, and AWS WAF rules.
Enterprise feature. Virtual patch rule content and deployable vendor exports (ModSecurity, Cloudflare, AWS WAF) are available to KEVIntel Enterprise users.
CVSS Scores
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Exploitation Status
Exploited in the wild
Recorded 2026-06-01 10:49:47 UTC · CVE
Used in malware
Recorded 2026-06-02 14:03:56 UTC · CVE
Proof of concept available
Recorded 2026-06-12 14:21:08 UTC · Nuclei Templates
Weaknesses (CWE)
-
Unrestricted Upload of File with Dangerous Type
Scanner Integrations
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2025/CVE-2025-52691.yaml | Jun 01, 2026 |
Recent Mentions
Daily CyberSecurity · Jun 08, 2026
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 RCE Flaws in MICI NetFax Server Unpatched, Vendor Refuses Fix CVE-2025-52691 (CVSS 10): Critical SmarterMail Flaw Opens Servers to Unauthenticated Attacks CISA Alert: Critical VMware vCenter RCE (CVSS 9.8) Now Exploited in the Wild
Potential Proof of Concepts
These PoCs are unverified and could contain malware. Use at your own risk.
nuclei · Created Unknown
Timeline
Key exploitation, disclosure, scanner coverage, and KEV attestation events for this CVE.
-
14:21 UTC about 1 month ago14:21 UTC · about 1 month ago
Public PoC available
Public proof-of-concept code published
-
02:20 UTC about 1 month ago02:20 UTC · about 1 month ago
KEV confirmed by Daily CyberSecurity
Exploitation attested by an external source
-
14:03 UTC about 2 months ago14:03 UTC · about 2 months ago
First public exploitation report
Exploit observed in malware
-
14:03 UTC about 2 months ago14:03 UTC · about 2 months ago
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
15:34 UTC about 2 months ago15:34 UTC · about 2 months ago
Nuclei template available
Scanner coverage available
-
10:49 UTC about 2 months ago10:49 UTC · about 2 months ago
Added to KEVIntel KEV Feed
High-confidence, third-party attested exploitation
-
02:15 UTC 7 months ago02:15 UTC · 7 months ago
CVE published
Vulnerability disclosed publicly
-
06:04 UTC about 1 year ago06:04 UTC · about 1 year ago
CVE ID reserved
Identifier reserved by the CNA
Automate This Intelligence with the Pro API
Confidence scoring, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
Pro API Example
GET /api/v2/pro/kevs/CVE-2025-52691
{
"cve_id": "CVE-2025-52691",
"title": "Upload Arbitrary Files",
"affected_vendor": "SmarterTools",
"affected_product": "SmarterMail",
"affected_versions": [
{ "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
],
"confidence": "Confirmed",
"cvss_score": 10.0,
"epss_score": 0.85457,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "...": "Pro API fields" },
"proof_of_concepts": [ "..." ],
"scanner_integrations": [ "..." ]
}