CVE-2025-4803 Overview
CVE-2025-4803 is a PHP Object Injection vulnerability in the Glossary by WPPedia WordPress plugin, affecting all versions up to and including 1.3.0. The flaw stems from unsafe deserialization of untrusted input passed through the posttypes parameter. Authenticated attackers with Administrator-level access can inject arbitrary PHP objects into the application. The plugin itself does not contain a Property-Oriented Programming (POP) chain, so exploitation requires another plugin or theme on the target site to provide one. When a POP chain is available, attackers can delete arbitrary files, exfiltrate sensitive data, or execute code. The issue is tracked under [CWE-502] Deserialization of Untrusted Data.
Critical Impact
Authenticated administrators can inject PHP objects that lead to arbitrary file deletion, data disclosure, or remote code execution when a POP chain is present from another installed component.
Affected Products
- Glossary by WPPedia – Best Glossary plugin for WordPress
- All versions up to and including 1.3.0
- WordPress sites with additional plugins or themes that expose a usable POP chain
Discovery Timeline
- 2025-05-21 - CVE-2025-4803 published to the National Vulnerability Database
- 2026-04-15 - Last updated in the NVD database
Technical Details for CVE-2025-4803
Vulnerability Analysis
The vulnerability is a classic PHP Object Injection issue introduced by calling unserialize() on attacker-controlled input. The plugin sanitizes settings input through a shared trait but passes the posttypes value through PHP's deserialization routine before validation. An authenticated administrator can submit a crafted serialized payload through the plugin's options handler. PHP then instantiates the encoded objects and invokes any matching magic methods such as __wakeup, __destruct, or __toString during processing.
The Glossary by WPPedia plugin does not ship a POP chain that turns object instantiation into a concrete primitive. However, WordPress installations commonly load several plugins and themes that define classes with dangerous magic methods. When such a chain exists in scope, the injected object can be chained into file operations, SQL queries, or arbitrary function calls. This makes the vulnerability a reliable escalation primitive on real-world WordPress sites rather than a theoretical issue.
Root Cause
The root cause is unsafe deserialization in the plugin's options handling logic. Sanitization code in core/classes/traits/trait-sanitizes-data.php processes settings without rejecting serialized payloads, and core/classes/class-options.php stores the resulting structure. See the WordPress Plugin Code and the GitHub Code Review for the affected paths.
Attack Vector
An authenticated user with Administrator privileges submits a serialized PHP object string as the value of the posttypes parameter when saving plugin settings. The plugin deserializes the value during option processing, triggering magic methods on the reconstructed objects. If a POP chain exists in another loaded plugin or theme, the chain executes within the WordPress process context. Network access to the WordPress admin interface is sufficient; no user interaction beyond the attacker's own session is required.
For further technical details, see the Wordfence Vulnerability Report.
Detection Methods for CVE-2025-4803
Indicators of Compromise
- POST requests to WordPress admin endpoints (such as options.php or plugin settings handlers) containing serialized PHP markers like O:, a:, or s: in the posttypes parameter.
- Unexpected changes to the wppedia options row in the wp_options table.
- Filesystem changes, new admin users, or outbound network connections originating from the PHP worker process shortly after settings updates.
- Presence of Glossary by WPPedia plugin at version 1.3.0 or earlier on production hosts.
Detection Strategies
- Inspect HTTP request bodies sent to plugin settings handlers for serialized PHP object signatures and reject payloads containing O: followed by class names.
- Enable PHP error and audit logging to capture warnings emitted by unserialize() when classes are missing or __wakeup throws.
- Correlate administrator login events with subsequent file modifications, database writes, or process spawns to surface object-injection-driven actions.
Monitoring Recommendations
- Track the installed version of Glossary by WPPedia across WordPress fleets and alert on any host still running 1.3.0 or earlier.
- Monitor web server access logs for repeated POST traffic to plugin admin pages from a single administrator session.
- Alert on web shell indicators such as new PHP files in wp-content/uploads/ or modifications to existing theme and plugin files.
How to Mitigate CVE-2025-4803
Immediate Actions Required
- Audit WordPress sites for the Glossary by WPPedia plugin and identify any instance at version 1.3.0 or below.
- Restrict Administrator accounts to trusted personnel and enforce strong, unique credentials with multi-factor authentication.
- Review installed plugins and themes for known POP chain gadgets and remove unused components that increase exploitation surface.
- Inspect the wppedia option values in the database for unexpected serialized content and reset them if tampering is suspected.
Patch Information
No fixed version is referenced in the NVD record at the time of publication. Site operators should monitor the plugin's WordPress.org listing and the Wordfence Vulnerability Report for an updated release that removes the unserialize() call on user-controlled input. Until a patched version is available, treat all installations at 1.3.0 or earlier as vulnerable.
Workarounds
- Deactivate and remove the Glossary by WPPedia plugin until a patched release is published.
- Use a Web Application Firewall (WAF) rule to block requests where the posttypes parameter contains serialized PHP object syntax.
- Limit access to wp-admin by IP allowlist or VPN to reduce the population of accounts that can reach the vulnerable settings page.
- Apply least privilege by demoting unnecessary Administrator accounts to lower roles that cannot reach the plugin settings handler.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
