CVE-2025-24777: Hillter Object Injection Vulnerability

CVE-2025-24777 Overview

CVE-2025-24777 is a PHP Object Injection vulnerability affecting the awethemes Hillter WordPress theme in versions up to and including 3.0.7. The flaw stems from deserialization of untrusted data [CWE-502], allowing authenticated attackers with low privileges to inject arbitrary PHP objects. When exploited alongside a suitable property-oriented programming (POP) chain present in WordPress core, other plugins, or themes, the issue can lead to remote code execution, file deletion, or sensitive data exposure. The vulnerability is exploitable over the network with low attack complexity.

Critical Impact

Authenticated attackers can trigger PHP Object Injection on affected Hillter installations, potentially leading to remote code execution, arbitrary file operations, and full site compromise.

Affected Products

• awethemes Hillter WordPress theme
• Versions from n/a through 3.0.7
• WordPress installations using the vulnerable theme

Discovery Timeline

• 2025-07-16 - CVE-2025-24777 published to NVD
• 2026-04-28 - Last updated in NVD database

Technical Details for CVE-2025-24777

Vulnerability Analysis

The Hillter theme passes attacker-controlled data into a PHP unserialize() operation without sufficient validation. PHP deserialization reconstructs objects from serialized strings and invokes magic methods such as __wakeup(), __destruct(), and __toString() during the process. When an attacker controls the serialized payload, these magic methods can be chained through existing classes to perform unintended actions.

This class of vulnerability is commonly referred to as PHP Object Injection. Exploitation in WordPress environments typically relies on a property-oriented programming gadget chain composed of classes loaded by WordPress core, the active theme, or any installed plugin. The presence of a usable chain determines whether the injection escalates to remote code execution, arbitrary file deletion, or data disclosure.

Root Cause

The root cause is improper handling of untrusted input passed to deserialization routines within the Hillter theme codebase. The theme accepts serialized data from a request context and deserializes it without integrity verification or type restrictions. This violates the secure coding guidance documented in CWE-502: Deserialization of Untrusted Data.

Attack Vector

An authenticated attacker with low-level privileges sends a crafted request containing a malicious serialized PHP payload to a vulnerable endpoint exposed by the Hillter theme. The server deserializes the payload, instantiating attacker-chosen objects and invoking magic methods. With an appropriate POP chain in scope, the attack can pivot to writing files, executing system commands, or modifying database records.

Further technical details are available in the Patchstack WordPress Vulnerability Report.

Detection Methods for CVE-2025-24777

Indicators of Compromise

• HTTP requests containing serialized PHP markers such as O:, a:, or s: in parameters processed by Hillter theme endpoints.
• Unexpected creation or modification of PHP files within the WordPress wp-content directory.
• New administrator accounts or unauthorized changes to WordPress options and user metadata.
• PHP error log entries referencing unserialize() calls or unexpected class instantiations.

Detection Strategies

• Inspect web server access logs for POST or GET parameters carrying serialized object signatures targeted at theme endpoints.
• Monitor PHP error logs for warnings about undefined classes or magic method invocations during deserialization.
• Audit WordPress files for integrity changes using checksum comparisons against known-good baselines of the Hillter theme.

Monitoring Recommendations

• Enable verbose logging on the WordPress site and forward logs to a centralized analytics platform for correlation.
• Alert on outbound network connections initiated by the PHP-FPM or web server process to unfamiliar destinations.
• Track authenticated user activity for low-privilege accounts performing requests to theme-controlled URLs.

How to Mitigate CVE-2025-24777

Immediate Actions Required

• Identify all WordPress sites using the awethemes Hillter theme version 3.0.7 or earlier.
• Restrict access to the WordPress admin area and reduce the number of low-privilege accounts where feasible.
• Deploy a web application firewall (WAF) rule to block requests containing PHP serialized object patterns to theme endpoints.
• Rotate WordPress secrets and credentials if compromise is suspected.

Patch Information

A fixed version beyond 3.0.7 must be obtained from the theme vendor. Review the Patchstack advisory for current remediation guidance and update the Hillter theme to the latest available release.

Workarounds

• Temporarily switch to an alternative theme if a patched Hillter version is not yet available.
• Apply virtual patching at the WAF layer to filter serialized PHP payloads in request parameters.
• Limit theme-related endpoints to authenticated administrators using server-level access controls until a fix is applied.

# Example WAF rule pattern to flag PHP serialized objects in request bodies
SecRule ARGS "@rx (^|&)[^=]+=\s*O:[0-9]+:\"" \
  "id:1024777,phase:2,deny,status:403,log,msg:'Potential PHP Object Injection - CVE-2025-24777'"