CVE-2025-47916: Invision Community RCE Vulnerability

CVE-2025-47916 Overview

CVE-2025-47916 is a critical remote code execution vulnerability affecting Invision Community 5.0.0 through versions prior to 5.0.7. The vulnerability exists within the theme editor functionality, specifically in the themeeditor.php controller, where a protected method can be invoked by unauthenticated users. This allows attackers to inject and execute arbitrary PHP code through crafted template strings, leading to complete server compromise.

Critical Impact

Unauthenticated attackers can achieve remote code execution on affected Invision Community installations by exploiting improper access controls in the theme editor, enabling full server compromise without requiring any credentials.

Affected Products

• Invision Community 5.0.0 through 5.0.6
• Installations using the front-end theme editor module (/applications/core/modules/front/system/themeeditor.php)
• Self-hosted Invision Community deployments

Discovery Timeline

• 2025-05-16 - CVE-2025-47916 published to NVD
• 2025-06-20 - Last updated in NVD database

Technical Details for CVE-2025-47916

Vulnerability Analysis

This vulnerability represents a severe code injection flaw stemming from improper access control combined with unsafe template evaluation. The issue resides in the themeeditor controller located at /applications/core/modules/front/system/themeeditor.php. A protected method named customCss can be invoked by unauthenticated users due to insufficient access control validation.

When this method is called, it accepts a content parameter and passes its value directly to the Theme::makeProcessFunction() method. This function evaluates the input through the template engine without proper sanitization, allowing attackers to inject malicious PHP code disguised as template directives.

Root Cause

The root cause is twofold: first, the customCss method lacks proper authentication checks, allowing unauthenticated access to what should be a privileged operation. Second, the Theme::makeProcessFunction() method evaluates user-supplied input as template code without adequate validation or sandboxing. This combination of CWE-94 (Improper Control of Generation of Code - Code Injection) and CWE-1336 (Improper Neutralization of Special Elements Used in a Template Engine) creates a direct path from unauthenticated HTTP requests to arbitrary PHP code execution.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker can craft a malicious HTTP request to the themeeditor.php endpoint, supplying a specially crafted content parameter containing template injection payloads. The template engine interprets these payloads and executes the embedded PHP code with the privileges of the web server process.

The exploitation flow involves:

1. Sending an unauthenticated request to the theme editor endpoint
2. Including malicious template syntax in the content parameter
3. The customCss method passes the content to Theme::makeProcessFunction()
4. The template engine evaluates the malicious input, executing arbitrary PHP code

Successful exploitation grants the attacker complete control over the web server, enabling data exfiltration, malware deployment, lateral movement, and persistent access. For detailed technical analysis, refer to the Karma Insecurity Advisory KIS-2025-02.

Detection Methods for CVE-2025-47916

Indicators of Compromise

• Unusual HTTP requests to /applications/core/modules/front/system/themeeditor.php from external IP addresses
• POST requests to the theme editor endpoint containing suspicious content parameters with PHP code patterns
• Web server logs showing requests with template injection syntax such as {php}, {eval}, or encoded PHP payloads
• Unexpected PHP processes spawned by the web server user account
• New or modified files in web-accessible directories with suspicious content

Detection Strategies

• Implement web application firewall (WAF) rules to detect template injection patterns in requests to theme editor endpoints
• Monitor access logs for unauthenticated requests to themeeditor.php with POST methods containing content parameters
• Deploy intrusion detection signatures for common PHP code injection patterns in HTTP request bodies
• Utilize endpoint detection and response (EDR) solutions to identify suspicious process creation by web server processes

Monitoring Recommendations

• Enable detailed logging for the Invision Community application and web server access logs
• Configure alerting for any access to theme editor endpoints from non-administrative IP addresses
• Implement file integrity monitoring on the Invision Community installation directory
• Monitor for outbound connections from the web server to unexpected external hosts

How to Mitigate CVE-2025-47916

Immediate Actions Required

• Upgrade Invision Community to version 5.0.7 or later immediately
• If immediate patching is not possible, disable or restrict access to the theme editor functionality
• Review web server logs for evidence of exploitation attempts targeting themeeditor.php
• Conduct a thorough security assessment of the server for signs of compromise if exploitation is suspected

Patch Information

Invision Community has addressed this vulnerability in version 5.0.7. Organizations running affected versions should apply the update immediately. The fix implements proper authentication checks on the customCss method and adds input validation to prevent template injection attacks.

Review the official Invision Community Release Notes for version 5.0.7 for complete patch details and upgrade instructions.

Workarounds

• Implement IP-based access restrictions to block external access to theme editor endpoints via web server configuration
• Deploy a web application firewall (WAF) with rules to detect and block template injection payloads
• Disable the front-end theme editor module if not required by modifying application permissions
• Place the Invision Community installation behind a VPN or other network access controls to limit exposure

# Example Apache configuration to restrict theme editor access
<Location "/applications/core/modules/front/system/themeeditor.php">
    Require ip 10.0.0.0/8
    Require ip 192.168.0.0/16
</Location>