CVE-2021-27964 Exploited in the Wild — SonLogger

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.

Source	Added
The Shadowserver First	2025-06-05 00:00 UTC

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/2021/CVE-2021-27964.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.

Not available

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.

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CVSS Scores

CVSS v3.1 9.8 Critical

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

CVSS v2.0 7.5 High

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

Proof of concept available

Recorded 2026-06-12 14:20:56 UTC · Nuclei Templates

Weaknesses (CWE)

CWE-434

Unrestricted Upload of File with Dangerous Type

Scanner Integrations

Nuclei, Metasploit, and other scanner references for this CVE are listed on the Detection tab.

Potential Proof of Concepts

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

SonLogger - Arbitrary File Upload

nuclei · Created Unknown

Timeline

Key exploitation, disclosure, scanner coverage, and KEV attestation events for this CVE.

12 Jun 2026 14:20 UTC about 2 months ago

12 Jun 2026 14:20 UTC · about 2 months ago

Public PoC available

Public proof-of-concept code published
1 Jun 2026 15:34 UTC 2 months ago

1 Jun 2026 15:34 UTC · 2 months ago

Nuclei template available

Scanner coverage available
5 Jun 2025 00:00 UTC about 1 year ago

5 Jun 2025 00:00 UTC · about 1 year ago

Added to KEVIntel KEV Feed

High-confidence, third-party attested exploitation
5 Mar 2021 01:37 UTC over 5 years ago

5 Mar 2021 01:37 UTC · over 5 years ago

CVE published

Vulnerability disclosed publicly
5 Mar 2021 00:00 UTC over 5 years ago

5 Mar 2021 00:00 UTC · over 5 years 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.

View Pro Pricing View API Docs

Pro API Example

GET /api/v2/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",
  "affected_versions": [
    { "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
  ],
  "confidence": "High",
  "cvss_score": 9.8,
  "epss_score": 0.47519,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "...": "Pro API fields" },
  "proof_of_concepts": [ "..." ],
  "scanner_integrations": [ "..." ]
}

The free JSON API returns basic KEV fields only. Confidence, telemetry, and artifact enrichment require Pro API access.

CVE-2021-27964

At a Glance

CVE References