CVE-2026-28074: Pizza House Object Injection Vulnerability

CVE-2026-28074 Overview

CVE-2026-28074 is a critical PHP Object Injection vulnerability affecting the ThemeREX Pizza House WordPress theme. The vulnerability stems from insecure deserialization of untrusted data, allowing attackers to inject malicious PHP objects into the application. When these serialized objects are processed by the vulnerable theme, attackers can achieve remote code execution, data manipulation, or complete site compromise without requiring authentication.

Critical Impact

Unauthenticated attackers can exploit this PHP Object Injection vulnerability to execute arbitrary code, potentially gaining full control of the WordPress installation and underlying server.

Affected Products

• ThemeREX Pizza House WordPress Theme versions through 1.4.0
• WordPress installations running the vulnerable Pizza House theme

Discovery Timeline

• 2026-03-05 - CVE CVE-2026-28074 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-28074

Vulnerability Analysis

This vulnerability is classified as CWE-502 (Deserialization of Untrusted Data). The ThemeREX Pizza House theme fails to properly validate and sanitize serialized data before passing it to PHP's unserialize() function. This allows attackers to craft malicious serialized payloads containing PHP objects that, when deserialized, trigger dangerous "magic methods" such as __wakeup(), __destruct(), or __toString().

The exploitation of this vulnerability requires no authentication and can be performed remotely over the network. The impact spans across confidentiality, integrity, and availability, as successful exploitation can lead to arbitrary file operations, code execution, database manipulation, and denial of service conditions.

Root Cause

The root cause of this vulnerability lies in the improper handling of user-supplied serialized data within the Pizza House theme. The theme accepts serialized input from untrusted sources and passes it directly to the unserialize() function without implementing proper validation, type checking, or allowlisting of acceptable object classes. This design flaw violates secure coding principles that mandate never trusting user input for deserialization operations.

Attack Vector

The attack is network-based and requires no prior authentication or user interaction. An attacker can submit a crafted HTTP request containing a malicious serialized PHP object to vulnerable endpoints within the theme. When the theme deserializes this payload, the injected object's magic methods are invoked automatically by PHP's serialization mechanism.

The attacker must identify a "POP chain" (Property Oriented Programming chain) consisting of classes within WordPress core, the theme, or installed plugins that contain exploitable magic methods. By chaining these methods together through object properties, the attacker can achieve arbitrary code execution or other malicious outcomes.

For detailed technical information about this vulnerability, refer to the Patchstack security advisory.

Detection Methods for CVE-2026-28074

Indicators of Compromise

• Unusual HTTP requests containing serialized PHP data (look for patterns like O:, a:, s: in request parameters)
• Web server logs showing POST requests with base64-encoded or URL-encoded serialized payloads targeting theme-specific endpoints
• Unexpected file modifications in the WordPress installation, particularly new PHP files or modified theme files
• Database entries containing serialized objects with unfamiliar class names

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect and block serialized PHP object patterns in incoming requests
• Implement log monitoring to identify requests containing unserialize() payload signatures such as O:[0-9]+: patterns
• Use file integrity monitoring (FIM) to detect unauthorized changes to WordPress core, theme, and plugin files
• Enable WordPress security plugins capable of detecting and alerting on suspicious deserialization attempts

Monitoring Recommendations

• Monitor web server access logs for anomalous POST requests to Pizza House theme endpoints
• Set up alerts for new PHP file creation within the WordPress installation directories
• Track outbound connections from the web server that may indicate post-exploitation activity
• Review WordPress user account creation logs for unauthorized administrator accounts

How to Mitigate CVE-2026-28074

Immediate Actions Required

• Deactivate and remove the ThemeREX Pizza House theme immediately if running version 1.4.0 or earlier
• Switch to a secure, actively maintained WordPress theme from a trusted source
• Audit the WordPress installation for signs of compromise including unauthorized files, users, or database modifications
• Review and harden WordPress security configurations including file permissions and database access controls

Patch Information

At the time of publication, no official patch has been confirmed for this vulnerability. Website administrators should monitor the Patchstack advisory for updates on remediation options. Consider contacting ThemeREX directly for information on patched versions.

Workarounds

• Remove or replace the Pizza House theme with an alternative secure theme until a patch is available
• Implement WAF rules to block requests containing serialized PHP object patterns
• Restrict access to WordPress admin areas using IP allowlisting or VPN requirements
• Apply the principle of least privilege to WordPress user accounts and database permissions

# Configuration example - WAF rule to block serialized PHP objects (ModSecurity)
SecRule REQUEST_BODY "@rx O:[0-9]+:\"" \
    "id:1001,\
    phase:2,\
    deny,\
    status:403,\
    msg:'Potential PHP Object Injection Attack Blocked',\
    severity:'CRITICAL'"