🚨 CVE-2021-23394 : CRITICAL REMOTE CODE EXECUTION ALERT 🚨 An unauthenticated remote code execution vulnerability has been disclosed in elFinder, a widely deployed web-based file manager, exploitable via malicious `.phar` file uploads and requiring no authentication or user interaction. Risk Severity: - High (CVSS 8.1, active exploitation, public exploits available, CISA KEV listed) Impact: - Unauthenticated remote code execution - Full web server compromise - Persistent webshell deployment - Sensitive data exfiltration - Ransomware and cryptominer installation Root Cause: - CWE-434 (Unrestricted File Upload) combined with CWE-502 (Deserialization of Untrusted Data). elFinder fails to block `.phar` file uploads. When accessed, PHP automatically deserializes malicious metadata embedded in the archive, triggering arbitrary code execution. Attackers can: - Upload a crafted `.phar` file via exposed elFinder upload endpoints - Trigger PHP deserialization by directly requesting the uploaded file - Execute arbitrary PHP code with web server privileges - Deploy persistent backdoors, mine cryptocurrency, or launch ransomware Are You Affected? - Vulnerable: All elFinder versions prior to 2.1.58 - Exposure: Internet-facing elFinder instances with upload functionality enabled Immediate Action Required: - Update: Upgrade to elFinder 2.1.58 or later immediately - Mitigation: Disable file uploads or block `.phar` extensions at the WAF/web server level if patching is delayed - Audit: Hunt for `.phar` files in upload directories and review logs for connector abuse This vulnerability is actively exploited and listed in CISA KEV. Unpatched systems should be considered compromised. 🛡️ #ostorlabCVE
Post summary
The alert highlights CVE‑2021‑23394 as a critical remote code execution flaw in elFinder that is actively exploited, with public exploits and a CISA KEV listing, and urges immediate patching or mitigation.