CVE-2021-27964
Medium PUBLISHEDSonLogger before 6.4.1 is affected by Unauthenticated Arbitrary File Upload. An attacker can send a POST request to...
Not yet in CISA KEV
Recommended Action
Treat as actively exploited. Assess exposure, apply compensating controls where patching is delayed, and monitor for abuse.
At a Glance
SonLogger before 6.4.1 is affected by Unauthenticated Arbitrary File Upload. An attacker can send a POST request to /Config/SaveUploadedHotspotLogoFile without any authentication or session header. There is no check for the file extension or content of the uploaded file.
- Published
- Mar 05, 2021
- First Seen
- Jun 05, 2025
- CVSS
- 9.8 Critical
- EPSS
- —
Recommended Actions
- Treat as actively exploited. Assess exposure, apply compensating controls where patching is delayed, and monitor for abuse.
- 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.
| Source | Added |
|---|---|
| The Shadowserver (via CIRCL) First | 2025-06-05 00:00 UTC |
Detection Context
Request patterns and scanner artifacts observed for this CVE. Operational detection logic guidance is coming soon.
Scanner Artifacts
Nuclei and Metasploit references linked to this CVE.
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-27964.yaml | Jun 01, 2026 |
CVSS Scores
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
AV:N/AC:L/Au:N/C:P/I:P/A:P
Exploitation Status
Exploited in the wild
Recorded 2025-06-05 00:00:00 UTC · The Shadowserver (via CIRCL)
Proof of concept available
Recorded 2026-06-12 14:20:56 UTC · Nuclei Templates
Scanner Integrations
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-27964.yaml | Jun 01, 2026 |
Potential Proof of Concepts
These PoCs are unverified and could contain malware. Use at your own risk.
nuclei · Created Unknown
Timeline
-
Proof of Concept Exploit Available
-
Detected by Nuclei
-
Added to KEVIntel
-
CVE Published to Public
-
CVE ID Reserved
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/v1/pro/kevs/CVE-2021-27964
{
"cve_id": "CVE-2021-27964",
"title": "SonLogger before 6.4.1 is affected by Unauthenticated Arbitrary File Upload. ...",
"affected_vendor": "SonLogger",
"affected_product": "SonLogger",
"confidence": "Medium",
"cvss_score": 9.8,
"epss_score": null,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "...": "Pro API fields" },
"proof_of_concepts": [ "..." ],
"scanner_integrations": [ "..." ]
}