CVE-2026-9773 Overview
CVE-2026-9773 is a command injection vulnerability in the Unraid web server that enables remote code execution. The flaw resides in ToggleState.php, which fails to properly validate a user-supplied string before passing it to a system call. Authenticated attackers can leverage this weakness to execute arbitrary commands in the context of the www-data user. The issue was reported through the Zero Day Initiative under tracking identifier ZDI-CAN-30134 and assigned [CWE-78] for OS Command Injection.
Critical Impact
Authenticated remote attackers can execute arbitrary code on Unraid installations as the www-data user, compromising confidentiality, integrity, and availability of the host.
Affected Products
- Unraid Web Server
- Unraid installations exposing the management web interface
- Affected component: ToggleState.php
Discovery Timeline
- 2026-06-24 - CVE-2026-9773 published to NVD
- 2026-06-25 - Last updated in NVD database
Technical Details for CVE-2026-9773
Vulnerability Analysis
The vulnerability exists in the ToggleState.php script of the Unraid web server. The script accepts a user-supplied string and passes it to a system call without sanitization or validation. Attackers can inject shell metacharacters into the input parameter to break out of the intended command context. Successful exploitation grants arbitrary command execution under the www-data service account.
Exploitation requires valid authentication to the Unraid web interface. Once authenticated, an attacker can issue a crafted HTTP request targeting ToggleState.php and append commands to the controlled input. The attack vector is network-based and the complexity is low. According to the Zero Day Initiative advisory ZDI-26-386, this is tracked as ZDI-CAN-30134.
Root Cause
The root cause is missing input validation on a user-controlled parameter consumed by a system call within ToggleState.php. The script concatenates attacker-supplied data into a shell command rather than escaping arguments or invoking the target binary directly with a safe API. This pattern matches [CWE-78], Improper Neutralization of Special Elements used in an OS Command.
Attack Vector
An attacker with valid web interface credentials sends an HTTP request to the vulnerable endpoint. The request contains shell metacharacters such as ;, |, &&, or backticks within the parameter consumed by ToggleState.php. The server passes the unsanitized string to a system shell, which executes the attacker payload alongside the intended command. The resulting process runs with the privileges of www-data, enabling reconnaissance, persistence, and lateral movement within the Unraid host.
No verified public exploit code is available at this time. Refer to the Zero Day Initiative Advisory ZDI-26-386 for technical details.
Detection Methods for CVE-2026-9773
Indicators of Compromise
- Unexpected child processes spawned by the Unraid web server under the www-data account.
- HTTP requests to ToggleState.php containing shell metacharacters such as ;, |, &, $(), or backticks.
- Outbound network connections originating from the web server process to unfamiliar destinations.
- New files, cron entries, or SSH keys created by the www-data user shortly after authenticated web sessions.
Detection Strategies
- Inspect web server access logs for requests targeting ToggleState.php with abnormally long or encoded query parameters.
- Correlate authenticated session activity with subsequent shell command execution events on the host.
- Deploy behavioral monitoring on the Unraid host to flag php or www-data processes spawning shells, wget, curl, or nc.
Monitoring Recommendations
- Enable verbose logging on the Unraid management interface and forward logs to a centralized SIEM for retention and analysis.
- Alert on any process tree where the web server is the parent of /bin/sh, /bin/bash, or interpreter binaries.
- Monitor authentication logs for unusual login times, source IPs, or repeated failures preceding command injection patterns.
How to Mitigate CVE-2026-9773
Immediate Actions Required
- Restrict access to the Unraid web interface to trusted management networks using firewall rules or VPN gating.
- Rotate all Unraid administrative credentials and enforce strong, unique passwords on every account.
- Audit existing user accounts and remove any unused or shared logins that could lower the authentication barrier.
- Review web server and shell history for prior exploitation attempts targeting ToggleState.php.
Patch Information
No vendor patch reference is listed in the available CVE data. Administrators should consult the Zero Day Initiative Advisory ZDI-26-386 and the Unraid vendor channels for updated firmware or patch releases addressing this issue.
Workarounds
- Place the Unraid management interface behind a reverse proxy that enforces network-level authentication and request filtering.
- Block or rate-limit HTTP requests containing shell metacharacters in parameters destined for ToggleState.php.
- Disable remote access to the web UI from untrusted networks until a vendor patch is applied.
- Apply least-privilege constraints to the www-data account and isolate the Unraid host within a dedicated VLAN.
# Configuration example: restrict Unraid web UI to a management subnet using iptables
iptables -A INPUT -p tcp --dport 80 -s 10.10.50.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 10.10.50.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
