CVE-2025-69111: Reisen PHP Object Injection Vulnerability

CVE-2025-69111 Overview

CVE-2025-69111 is an unauthenticated PHP Object Injection vulnerability affecting the Reisen WordPress theme in versions 1.4.1 and earlier. The flaw stems from insecure deserialization of attacker-controlled input [CWE-502]. Remote attackers can exploit the issue over the network without authentication or user interaction. Successful exploitation can lead to arbitrary code execution, data tampering, or full site compromise when a suitable PHP object gadget chain exists in the WordPress environment.

Critical Impact
Unauthenticated remote attackers can trigger PHP object instantiation that may result in arbitrary code execution and full compromise of affected WordPress sites running the Reisen theme.

Affected Products

Reisen WordPress theme versions <= 1.4.1
WordPress installations using the Reisen theme as active or installed template
Any WordPress site exposing endpoints that deserialize Reisen-controlled input

Discovery Timeline

2026-06-17 - CVE-2025-69111 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-69111

Vulnerability Analysis

The vulnerability is classified as Deserialization of Untrusted Data [CWE-502]. The Reisen theme passes attacker-controlled data into a PHP unserialize() call without validating its origin or structure. PHP deserialization instantiates objects and triggers magic methods such as __wakeup() and __destruct() during the parsing process.

When an attacker supplies a crafted serialized payload, the PHP engine invokes these magic methods on attacker-chosen classes. By combining classes loaded by WordPress core, plugins, or the theme itself, an attacker can construct gadget chains. These chains can lead to arbitrary file write, SQL execution, or remote code execution depending on the loaded code base.

The issue is exploitable across the network with low attack complexity and requires no privileges or user interaction. This combination makes the vulnerability suitable for mass scanning and automated exploitation against exposed WordPress sites.

Root Cause

The root cause is the use of PHP unserialize() on data that crosses a trust boundary without prior cryptographic validation or strict type filtering. WordPress provides safer alternatives such as maybe_unserialize() paired with allowlists, but neither mitigates object injection when the input itself is attacker-controlled.

Attack Vector

The attack vector is network-based. An attacker submits a serialized PHP payload to a vulnerable Reisen theme endpoint, typically through a parameter, cookie, or AJAX action handled by the theme. The serialized blob references classes available in the WordPress runtime and chains their magic methods to reach a sensitive sink such as file write, eval(), or database modification.

No working exploit code is publicly listed for CVE-2025-69111 at the time of writing. Technical details are described in the Patchstack WordPress Vulnerability Advisory.

Detection Methods for CVE-2025-69111

Indicators of Compromise

HTTP requests to Reisen theme endpoints containing serialized PHP markers such as O:, a:, or s: followed by class names and length prefixes
Unexpected PHP files created under wp-content/uploads/ or theme directories after suspicious requests
New or modified WordPress administrator accounts created without a corresponding admin login event
Outbound network connections from the web server to unknown hosts shortly after theme requests

Detection Strategies

Inspect web server and WordPress access logs for request parameters containing PHP serialization syntax targeting Reisen theme routes
Enable PHP error logging and alert on warnings from unserialize() referencing undefined classes
Monitor file integrity on wp-content/themes/reisen/ and the broader WordPress installation for unauthorized modifications

Monitoring Recommendations

Forward web access logs, PHP error logs, and WordPress audit logs to a centralized analytics platform for correlation
Alert on POST requests to theme endpoints whose body or query string contains serialized object patterns
Track creation of PHP files in writable WordPress directories and flag any execution of those files

How to Mitigate CVE-2025-69111

Immediate Actions Required

Identify all WordPress sites using the Reisen theme and confirm the installed version
Upgrade the Reisen theme to a version higher than 1.4.1 once the vendor publishes a fix
Temporarily disable or replace the Reisen theme on production sites that cannot be patched immediately
Rotate WordPress administrator credentials, secret keys in wp-config.php, and database passwords if exploitation is suspected

Patch Information

No fixed version is referenced in the NVD entry at publication time. Site operators should consult the Patchstack WordPress Vulnerability Advisory for vendor patch status and apply updates as soon as they are released.

Workarounds

Deploy a Web Application Firewall (WAF) rule that blocks request parameters matching PHP serialization signatures such as O:<digit>:" and a:<digit>:{
Restrict access to Reisen theme endpoints to known administrative IP addresses where feasible
Apply virtual patching through Patchstack or an equivalent WordPress protection service until an official theme update is available

bash

# Example ModSecurity rule to block PHP serialized objects in request bodies
SecRule REQUEST_BODY|ARGS "@rx O:\d+:\"[A-Za-z_\\\\]+\":\d+:\{" \
    "id:1069111,phase:2,deny,status:403,log,\
    msg:'Potential PHP Object Injection targeting Reisen theme (CVE-2025-69111)'"