CVE-2026-39446: Kapee PHP Object Injection Vulnerability

CVE-2026-39446 Overview

CVE-2026-39446 is an unauthenticated PHP Object Injection vulnerability affecting the Kapee WordPress theme in versions prior to 1.7.0. The flaw stems from insecure deserialization of untrusted input [CWE-502], allowing remote attackers to inject crafted PHP objects without authentication. When combined with a suitable property-oriented programming (POP) gadget chain present in WordPress core, plugins, or the theme itself, exploitation can lead to remote code execution, arbitrary file operations, or data tampering. The vulnerability is tracked by Patchstack and impacts any WordPress site running an affected Kapee theme build.

Critical Impact
Unauthenticated attackers can submit malicious serialized payloads to vulnerable Kapee theme endpoints, triggering object instantiation that may escalate to remote code execution through gadget chains.

Affected Products

Kapee WordPress theme versions prior to 1.7.0
WordPress installations using the Kapee theme
E-commerce sites built on Kapee with WooCommerce integrations

Discovery Timeline

2026-06-17 - CVE-2026-39446 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2026-39446

Vulnerability Analysis

The Kapee theme passes attacker-controlled input to PHP's unserialize() function without validating the data source or restricting allowed classes. PHP Object Injection occurs when untrusted serialized strings are deserialized, causing the PHP runtime to instantiate arbitrary classes and invoke magic methods such as __wakeup(), __destruct(), or __toString(). Attackers leverage these magic methods through POP gadget chains to redirect application flow toward dangerous sinks.

The issue is unauthenticated, meaning no valid WordPress session is required. Attackers can target the vulnerable endpoint directly over HTTP or HTTPS. Successful exploitation depends on the presence of usable gadgets in loaded PHP code, which is common on WordPress installations that load WooCommerce, Elementor, or other large plugins alongside the Kapee theme.

The EPSS score is 0.395% as of 2026-06-18, reflecting current exploitation likelihood estimates while the vulnerability remains newly disclosed.

Root Cause

The root cause is improper input handling around unserialize() calls within the Kapee theme prior to version 1.7.0. The theme deserializes data originating from HTTP request parameters, cookies, or other client-controlled channels without integrity checks, signature validation, or use of safe alternatives such as json_decode().

Attack Vector

An attacker crafts a serialized PHP object string referencing a class that exists within the WordPress runtime. The attacker then submits this payload to the vulnerable Kapee endpoint over the network. PHP deserializes the payload, instantiates the referenced class, and triggers magic methods that execute attacker-defined operations. Attack complexity is rated high because exploitation requires identifying a working gadget chain in the target environment.

No verified public proof-of-concept code is currently available. Refer to the Patchstack WordPress Vulnerability advisory for additional technical context.

Detection Methods for CVE-2026-39446

Indicators of Compromise

HTTP requests containing serialized PHP patterns such as O:8:, a:1:{, or s:N: in query strings, POST bodies, or cookies targeting Kapee theme endpoints.
Unexpected PHP error log entries referencing unserialize(), __wakeup, or __destruct from theme files under wp-content/themes/kapee/.
Creation of new PHP files in wp-content/uploads/ or modification of theme files outside of update windows.
Outbound network connections initiated by the PHP-FPM or web server process to unfamiliar hosts.

Detection Strategies

Inspect web server access logs for request parameters that begin with PHP serialization tokens, then correlate with requests reaching Kapee theme paths.
Enable WordPress audit logging to record administrative actions, user creation events, and option changes that follow suspicious requests.
Deploy a web application firewall rule that blocks serialized PHP object signatures on unauthenticated endpoints.

Monitoring Recommendations

Monitor file integrity on the wp-content/themes/kapee/ directory and core WordPress directories for unauthorized changes.
Alert on new administrator accounts, scheduled tasks, or wp_options modifications that occur without a corresponding admin session.
Track outbound DNS and HTTP traffic from web hosts to identify command-and-control callbacks after successful exploitation.

How to Mitigate CVE-2026-39446

Immediate Actions Required

Update the Kapee theme to version 1.7.0 or later on all WordPress sites.
Audit wp-content/themes/kapee/ and the broader WordPress installation for webshells, backdoors, or unauthorized administrator accounts.
Rotate WordPress secret keys in wp-config.php and reset all administrator passwords if compromise is suspected.
Restrict access to the WordPress admin and theme endpoints behind a web application firewall while patching is completed.

Patch Information

The vendor addressed the issue in Kapee theme version 1.7.0. Administrators should apply the update through the WordPress admin dashboard or by replacing the theme files directly. See the Patchstack advisory for vendor confirmation and version details.

Workarounds

Apply virtual patching through a web application firewall to block requests containing serialized PHP object signatures.
Disable the Kapee theme and switch to a default WordPress theme until patching is complete on production sites.
Restrict access to vulnerable theme endpoints by IP allowlist at the reverse proxy or WAF layer.

bash

# Example ModSecurity rule to block serialized PHP objects in requests
SecRule ARGS|REQUEST_COOKIES|REQUEST_HEADERS "@rx (?i)(O|a):[0-9]+:\"" \
  "id:1039446,phase:2,deny,status:403,log,\
   msg:'Possible PHP Object Injection payload (CVE-2026-39446)'"