CVE-2026-30460: Fuel CMS Authenticated RCE Vulnerability

CVE-2026-30460 Overview

Daylight Studio FuelCMS v1.5.2 was discovered to contain an authenticated remote code execution (RCE) vulnerability in the Blocks module. This vulnerability allows authenticated attackers with access to the CMS administrative panel to execute arbitrary code on the underlying server, potentially leading to complete system compromise.

FuelCMS is a popular open-source content management system built on the CodeIgniter PHP framework, used by organizations for website management and content delivery. The vulnerability specifically affects the Blocks module, which handles template blocks and content components within the CMS.

Critical Impact

Authenticated attackers can achieve full remote code execution on the server hosting FuelCMS, enabling complete system takeover, data exfiltration, and lateral movement within the network.

Affected Products

• Daylight Studio FuelCMS version 1.5.2
• thedaylightstudio fuel_cms (cpe:2.3:a:thedaylightstudio:fuel_cms:1.5.2:*:*:*:*:*:*:*)

Discovery Timeline

• April 7, 2026 - CVE-2026-30460 published to NVD
• April 9, 2026 - Last updated in NVD database

Technical Details for CVE-2026-30460

Vulnerability Analysis

This vulnerability is classified as CWE-94 (Improper Control of Generation of Code, also known as Code Injection). The flaw exists within the Blocks module of FuelCMS, where user-supplied input is improperly processed, allowing an authenticated user to inject and execute arbitrary code on the server.

The attack requires authentication to the FuelCMS administrative interface, meaning the attacker must possess valid credentials or have compromised an existing account. Once authenticated, the attacker can leverage the Blocks module functionality to inject malicious code that will be executed in the context of the web server process.

The vulnerability is exploitable over the network with low attack complexity, requiring no user interaction beyond the initial authentication. Successful exploitation results in high impact to confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause of this vulnerability stems from insufficient input validation and improper sanitization within the Blocks module of FuelCMS. When processing block content or template data, the application fails to adequately validate or escape user-controlled input before it is processed by the PHP interpreter or executed as server-side code.

This lack of proper input handling allows malicious code to be injected through the Blocks module interface and subsequently executed on the server, bypassing expected security controls.

Attack Vector

The attack vector for CVE-2026-30460 is network-based, requiring the attacker to have authenticated access to the FuelCMS administrative panel. The exploitation flow typically involves:

1. The attacker authenticates to the FuelCMS administrative interface using valid credentials
2. The attacker navigates to the Blocks module within the CMS admin panel
3. Through the Blocks module interface, the attacker injects malicious PHP code or commands
4. The injected code is executed by the server, granting the attacker control over the underlying system

The vulnerability manifests in the Blocks module's handling of user input. Technical details regarding the specific injection point and exploitation methodology are available in the Pentest Tools Analysis Document. For additional information, refer to the GitHub FUEL-CMS Repository.

Detection Methods for CVE-2026-30460

Indicators of Compromise

• Unusual PHP process spawning child processes such as cmd.exe, /bin/sh, or /bin/bash
• Unexpected file modifications or creations within the FuelCMS installation directory
• Anomalous network connections originating from the web server process
• Log entries showing repeated access to Blocks module endpoints with suspicious payloads
• Web shell files appearing in the FuelCMS directory structure

Detection Strategies

• Monitor FuelCMS administrative access logs for unusual activity patterns in the Blocks module
• Implement file integrity monitoring on FuelCMS installation directories to detect unauthorized changes
• Configure web application firewall (WAF) rules to detect code injection patterns in POST requests to administrative endpoints
• Enable verbose logging for PHP execution and monitor for anomalous code execution patterns

Monitoring Recommendations

• Deploy real-time log analysis for FuelCMS administrative actions, particularly in the Blocks module
• Implement network-level monitoring for outbound connections from web servers that may indicate reverse shell activity
• Configure alerting for any new file creations within the web application directory that occur outside of normal deployment processes
• Monitor for privilege escalation attempts following initial web server compromise

How to Mitigate CVE-2026-30460

Immediate Actions Required

• Audit all FuelCMS administrative accounts and remove unnecessary access privileges
• Implement strong multi-factor authentication (MFA) for all administrative accounts
• Apply network segmentation to limit access to FuelCMS administrative interfaces from trusted networks only
• Review recent activity in the Blocks module for signs of exploitation
• Consider temporarily disabling the Blocks module if not critical to operations until a patch is available

Patch Information

As of the last NVD update on April 9, 2026, no official patch information has been published by Daylight Studio. Organizations should monitor the FuelCMS Official Site and the GitHub FUEL-CMS Repository for security updates and patch releases.

In the absence of an official patch, organizations should implement the workarounds and mitigations described below to reduce the risk of exploitation.

Workarounds

• Restrict access to the FuelCMS administrative interface to specific IP addresses or VPN connections only
• Implement additional authentication layers (IP whitelisting, VPN requirement) for administrative access
• Deploy a web application firewall (WAF) with rules to detect and block code injection attempts
• Conduct a thorough review of all administrative user accounts and enforce the principle of least privilege
• Consider migrating to an alternative CMS if the Blocks module is not essential and no patch becomes available

# Example: Restrict FuelCMS admin access via Apache .htaccess
# Place in the FuelCMS fuel/modules/fuel/views/blocks directory

<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteCond %{REMOTE_ADDR} !^192\.168\.1\. 
    RewriteCond %{REMOTE_ADDR} !^10\.0\.0\.
    RewriteRule ^(.*)$ - [F,L]
</IfModule>

# Alternatively, restrict via nginx location block
# location /fuel/blocks {
#     allow 192.168.1.0/24;
#     allow 10.0.0.0/8;
#     deny all;
# }