KEV Intelligence

Vulnerability report

Exploited in the wild High confidence Not in CISA KEV

CVE-2021-21307

Remote Code Exploit in Lucee Admin

lucee / Lucee · >= 5.3.5.0, < 5.3.5.96

View live feed Monitor via API Watch CVE
Severity
CVSS 8.6 · High
Confidence
High
Exploit status
Exploited in the wild
EPSS
89.2%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2021-21307 is an unauthenticated Remote Code Exploit in Lucee Admin. Lucee Server is a dynamic, Java based (JSR-223), tag and scripting language used for rapid web application development. In Lucee Admin before...

Is it exploited?

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

Who is affected?

lucee / Lucee >= 5.3.5.0, < 5.3.5.96.

What should we do?

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

Overview

Lucee Server is a dynamic, Java based (JSR-223), tag and scripting language used for rapid web application development

Lucee Server is a dynamic, Java based (JSR-223), tag and scripting language used for rapid web application development. In Lucee Admin before versions 5.3.7.47, 5.3.6.68 or 5.3.5.96 there is an unauthenticated remote code exploit.

This is fixed in versions 5.3.7.47, 5.3.6.68 or 5.3.5.96. As a workaround, one can block access to the Lucee Administrator.

Vendor Product Affected Status
lucee Lucee >= 5.3.5.0, < 5.3.5.96 Affected
lucee Lucee >= 5.3.6.0, < 5.3.6.68 Affected
lucee Lucee >= 5.3.7.0, < 5.3.7.47 Affected
Published
11 Feb 2021
Exploitation Reported
22 Apr 2025
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

nuclei_scanner metasploit java

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

The Shadowserver

Recorded 22 Apr 2025

Independent exploitation attestation added to the KEV Intelligence record.

Proof of concept available

Nuclei Templates

Recorded 28 Apr 2025

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.

Learn about Pro API access
Source Added
The Shadowserver First 2025-04-22 00:00 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
Metasploit https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/http/lucee_admin_imgprocess_file_write.rb 28 Apr 2025
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-21307.yaml 25 Apr 2025

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

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

EPSS

89.2%

Weaknesses

Missing Authorization CWE-862

Potential Proof of Concepts

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

Lucee Admin - Remote Code Execution

nuclei · Created Unknown

lucee_admin_imgprocess_file_write

metasploit · Created Unknown

Metasploit module for CVE-2021-21307

Timeline

From disclosure to observed exploitation

  1. Metasploit module available

    Exploit module available

  2. Public PoC available

    Public proof-of-concept code published

  3. Nuclei template available

    Scanner coverage available

  4. Added to KEV Intelligence KEV Feed

    High-confidence, third-party attested exploitation

  5. CVE published

    Vulnerability disclosed publicly

  6. 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.

View Pro pricing Read API docs
  • 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-2021-21307

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2021-21307",
  "confidence": "High",
  "cvss_score": 8.6,
  "cvss_estimated": false,
  "epss_score": 0.89189,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}

Early warning alerts

Get alerts on high-impact exploitation

Receive curator-selected alerts when exploitation activity warrants attention. Each alert includes the evidence and context needed to decide what requires attention now.

Occasional high-impact alerts. Unsubscribe anytime. See our Privacy Policy.