CVE-2026-25029: KIDZ Object Injection Vulnerability

CVE-2026-25029 Overview

CVE-2026-25029 is a PHP Object Injection vulnerability in the KIDZ WordPress theme by park_of_ideas. The flaw stems from insecure deserialization of untrusted data [CWE-502] and affects all theme versions up to and including 5.24. Unauthenticated attackers can submit crafted serialized payloads over the network to trigger object instantiation within the application context. When combined with a suitable property-oriented programming (POP) chain present in the theme, WordPress core, or other installed plugins, the issue can lead to remote code execution, arbitrary file operations, or full site compromise.

Critical Impact
Unauthenticated network attackers can inject PHP objects into the KIDZ theme through versions 5.24, potentially achieving remote code execution and full WordPress site takeover.

Affected Products

park_of_ideas KIDZ WordPress theme versions through 5.24
WordPress sites using the KIDZ theme as the active or installed theme
Multisite WordPress deployments where KIDZ is network-enabled

Discovery Timeline

2026-03-25 - CVE-2026-25029 published to the National Vulnerability Database (NVD)
2026-04-24 - Last updated in NVD database

Technical Details for CVE-2026-25029

Vulnerability Analysis

The KIDZ theme passes attacker-controlled input into a PHP deserialization function without validating the data type or origin. PHP's unserialize() reconstructs arbitrary objects from a serialized string and invokes magic methods such as __wakeup(), __destruct(), and __toString() during object lifecycle events. Attackers exploit these automatic method calls by chaining gadgets from loaded classes to reach sensitive sinks like file writes, SQL execution, or command execution. The network attack vector and lack of authentication requirements make this issue exploitable against any internet-exposed WordPress instance running the affected theme.

Root Cause

The root cause is the unsafe use of PHP deserialization on untrusted input within the KIDZ theme codebase. The theme accepts serialized data from a request parameter, cookie, or stored option and feeds it into unserialize() without integrity checks or allow-listing of permitted classes. CWE-502 describes this exact pattern, where deserialized data drives runtime object construction.

Attack Vector

Exploitation requires only network access to the WordPress site. An attacker sends an HTTP request containing a serialized PHP object payload to a theme endpoint that processes the input. The deserialization call instantiates the attacker-supplied class graph and triggers gadget chains during execution. No user interaction or prior authentication is needed. Public exploitation details are documented in the Patchstack Vulnerability Report.

Detection Methods for CVE-2026-25029

Indicators of Compromise

HTTP requests containing serialized PHP markers such as O:, a:, or s: followed by length and class names in query strings, POST bodies, or cookies targeting theme endpoints.
Unexpected PHP files written to wp-content/uploads/ or theme directories, often with randomized names or web shell signatures.
New or modified WordPress administrator accounts created without corresponding legitimate admin activity.
Outbound network connections from the web server to attacker-controlled infrastructure after suspicious POST traffic.

Detection Strategies

Inspect web server access logs for serialized object patterns in parameters processed by the KIDZ theme.
Monitor PHP error logs for __wakeup, __destruct, or class instantiation warnings that indicate failed or partial deserialization attempts.
Apply WordPress integrity monitoring to detect changes to core files, theme files, and plugin files outside of update windows.
Correlate web request anomalies with file system and process telemetry to surface post-exploitation activity.

Monitoring Recommendations

Deploy a Web Application Firewall (WAF) rule that blocks requests containing PHP serialized object signatures.
Enable file integrity monitoring (FIM) on wp-content/themes/kidz/ and the WordPress root directory.
Forward web, PHP-FPM, and host telemetry to a centralized analytics platform for cross-source correlation.
Alert on PHP processes spawning shell interpreters such as sh, bash, or cmd.exe.

How to Mitigate CVE-2026-25029

Immediate Actions Required

Deactivate the KIDZ theme on any site running version 5.24 or earlier until a vendor patch is verified and applied.
Apply WAF signatures that block PHP serialized payloads sent to WordPress endpoints.
Audit administrator accounts, scheduled tasks (wp_cron), and recently modified files for signs of compromise.
Rotate WordPress secrets in wp-config.php, database credentials, and administrator passwords if exploitation is suspected.

Patch Information

At the time of publication, the Patchstack advisory lists the issue as affecting KIDZ through version 5.24. Site operators should consult the Patchstack Vulnerability Report for the latest fixed-version information from park_of_ideas and update immediately once a patched release is available.

Workarounds

Switch to a different actively maintained WordPress theme until a fixed KIDZ release is published.
Restrict access to WordPress administrative and theme endpoints by source IP where feasible.
Use a virtual patching capability in a WAF or reverse proxy to drop requests containing serialized object syntax.
Disable PHP deserialization in unused code paths and enforce least-privilege file permissions on the web server.

bash

# Example WAF rule (ModSecurity) blocking PHP serialized payloads
SecRule ARGS|REQUEST_COOKIES|REQUEST_HEADERS \
  "@rx (?:^|[^a-zA-Z0-9])O:\d+:\"[a-zA-Z_\\\\]+\":\d+:\{" \
  "id:1002601,phase:2,deny,status:403,log,\
   msg:'Possible PHP Object Injection (CVE-2026-25029)'"