CVE-2026-24974: CitiLights Object Injection Vulnerability

CVE-2026-24974 Overview

CVE-2026-24974 is a Deserialization of Untrusted Data vulnerability in the NooTheme CitiLights WordPress theme (noo-citilights) that allows attackers to perform PHP Object Injection attacks. This vulnerability arises from improper handling of serialized data, enabling authenticated attackers with low privileges to inject malicious PHP objects into the application.

Critical Impact

Successful exploitation of this vulnerability could allow an authenticated attacker to achieve remote code execution, data manipulation, or denial of service by injecting malicious serialized PHP objects that are deserialized by the application.

Affected Products

• NooTheme CitiLights WordPress Theme version 3.7.1 and earlier
• WordPress installations running the noo-citilights theme
• All versions from initial release through 3.7.1

Discovery Timeline

• 2026-03-25 - CVE-2026-24974 published to NVD
• 2026-03-26 - Last updated in NVD database

Technical Details for CVE-2026-24974

Vulnerability Analysis

This vulnerability is classified under CWE-502 (Deserialization of Untrusted Data). The CitiLights WordPress theme fails to properly validate and sanitize serialized data before passing it to PHP's unserialize() function. When user-controlled input is deserialized without adequate validation, an attacker can craft malicious serialized objects that, when instantiated, trigger dangerous operations through PHP's magic methods such as __wakeup(), __destruct(), or __toString().

The network-accessible attack vector combined with low authentication requirements and no user interaction needed makes this vulnerability particularly concerning for WordPress sites using this theme. Successful exploitation can impact the confidentiality, integrity, and availability of the affected system.

Root Cause

The root cause of this vulnerability lies in the CitiLights theme's implementation of serialization handling. The theme accepts serialized PHP data from user input and passes it directly to the unserialize() function without implementing proper validation, filtering, or using safe deserialization alternatives. This allows attackers to inject arbitrary PHP objects that can leverage existing class autoloaders and gadget chains present in WordPress core, plugins, or the theme itself to achieve code execution.

Attack Vector

The attack is executed over the network and requires low-privilege authentication to the WordPress installation. An attacker with subscriber-level access or higher can submit crafted serialized payloads through theme functionality that processes user input. When the malicious payload is deserialized, it instantiates attacker-controlled objects that exploit PHP Property-Oriented Programming (POP) chains to execute arbitrary code or perform other malicious actions.

The exploitation process typically involves:

1. Identifying deserialization entry points in the theme
2. Discovering usable gadget chains in the WordPress environment
3. Crafting a malicious serialized payload that chains multiple classes
4. Submitting the payload through an authenticated request
5. The server deserializes the payload, triggering the malicious chain

For detailed technical analysis, see the Patchstack vulnerability database entry.

Detection Methods for CVE-2026-24974

Indicators of Compromise

• Unusual serialized data patterns in HTTP request parameters, particularly containing PHP object signatures like O: followed by class names
• Unexpected PHP errors or crashes related to object instantiation in WordPress error logs
• Anomalous file creation or modification in WordPress directories following authenticated user requests
• Suspicious outbound network connections originating from the web server process

Detection Strategies

• Monitor web application firewall (WAF) logs for requests containing serialized PHP object patterns targeting the CitiLights theme endpoints
• Implement file integrity monitoring on WordPress theme and plugin directories to detect unauthorized modifications
• Review PHP error logs for deserialization-related exceptions or unexpected class instantiation errors
• Deploy runtime application self-protection (RASP) solutions capable of detecting deserialization attacks

Monitoring Recommendations

• Enable detailed access logging for all WordPress administrative and theme-related endpoints
• Configure alerts for authentication events followed by unusual request patterns to theme-specific URLs
• Implement network monitoring for unexpected outbound connections from web servers
• Set up regular security scans using WordPress-specific vulnerability scanners

How to Mitigate CVE-2026-24974

Immediate Actions Required

• Update the CitiLights theme to a patched version when available from NooTheme
• If no patch is available, consider temporarily disabling or replacing the CitiLights theme
• Restrict user registration and minimize the number of authenticated users with access to the site
• Implement a Web Application Firewall (WAF) with rules to block serialized PHP object injection attempts
• Review and audit all user accounts for unauthorized access or suspicious activity

Patch Information

No official patch information is currently available from the vendor. Website administrators should monitor the Patchstack vulnerability database and the NooTheme official channels for security updates. Until a patch is released, implementing the workarounds below is strongly recommended.

Workarounds

• Deploy a WAF rule to filter requests containing serialized PHP object signatures (patterns matching /O:\d+:"/ regex)
• Implement input validation at the server level to reject requests with serialized data before they reach the application
• Consider using WordPress security plugins that provide object injection protection such as Wordfence or Sucuri
• Restrict file system permissions to prevent the web server from writing to theme and plugin directories

# Configuration example - Apache mod_security rule to block PHP object injection
SecRule ARGS "@rx O:\d+:\"" "id:1001,phase:2,deny,status:403,msg:'PHP Object Injection Attempt Blocked'"