Unraid 6.8.0 and Prior Remote Code Execution (RCE) and Authentication Bypass Vulnerability Analysis (CVE-2020-5847)

1. Vulnerability Overview & Root Cause

This vulnerability (CVE-2020-5847) is a critical remote code execution (RCE) vulnerability in the web management interface of Unraid, a network-attached storage (NAS) operating system. The root cause lies in the web server's failure to properly sanitize and validate user-supplied input before passing it to internal PHP functions or system command execution contexts. This allows unauthenticated attackers to execute arbitrary system commands by sending specially crafted HTTP requests.

2. Exploitation Mechanics & Attack Scenario

Attackers target specific PHP scripts (such as extract.php or endpoints handling query string parameters) within the Unraid web interface. The exploitation scenario typically unfolds as follows:

• The attacker scans for Unraid servers with web management ports (TCP 80/443) exposed to the public internet.
• By leveraging authentication bypass flaws (such as CVE-2020-5849) or insufficient session validation, the attacker bypasses the login barrier.
• The attacker injects shell commands into the vulnerable parameters and transmits them via HTTP GET or POST requests.
• Since the Unraid web server runs with root privileges, the injected commands are executed immediately with administrative rights, allowing the attacker to establish a reverse shell or download malware.

3. Infrastructure & Business Impact

Unraid OS is widely utilized for hosting critical data backups, media servers, and virtualized environments. Successful exploitation of this vulnerability allows attackers to access, modify, or delete all sensitive data stored on the NAS. Furthermore, compromised systems can be infected with ransomware or used as a pivot point to compromise the broader internal network. Given its inclusion in the CISA KEV catalog, active exploitation in the wild makes immediate remediation imperative.