CVE-2025-46481 Overview
CVE-2025-46481 is a PHP Object Injection vulnerability in the Michael Cannon Flickr Shortcode Importer plugin for WordPress. The flaw stems from insecure deserialization of untrusted data [CWE-502] and affects all versions of the flickr-shortcode-importer plugin up to and including 2.2.3. An authenticated attacker with high privileges can submit crafted serialized payloads that the plugin deserializes, triggering object instantiation in the WordPress runtime. When suitable POP (Property-Oriented Programming) gadgets exist in loaded plugins or themes, this leads to compromise of confidentiality, integrity, and availability.
Critical Impact
Successful exploitation enables PHP Object Injection on the WordPress server, which can escalate to arbitrary file operations, data theft, or remote code execution depending on available gadget chains.
Affected Products
- Michael Cannon Flickr Shortcode Importer (flickr-shortcode-importer) WordPress plugin
- All versions through 2.2.3
- WordPress installations with the affected plugin active
Discovery Timeline
- 2025-04-24 - CVE-2025-46481 published to the National Vulnerability Database
- 2026-04-23 - Last updated in NVD database
Technical Details for CVE-2025-46481
Vulnerability Analysis
The Flickr Shortcode Importer plugin deserializes attacker-controlled input without validation. PHP's unserialize() function reconstructs arbitrary object graphs from serialized strings and invokes magic methods such as __wakeup(), __destruct(), and __toString() during the lifecycle of those objects. When the plugin passes unsanitized data into unserialize(), attackers can craft payloads that trigger gadget chains in any loaded class.
The vulnerability requires authentication with high privileges, which limits opportunistic attacks but remains exploitable in multi-author WordPress deployments, compromised editor accounts, or environments where lower-tier admin roles have been delegated. PHP Object Injection in WordPress historically chains with gadgets in plugins, themes, and core libraries to achieve arbitrary file write or command execution.
Root Cause
The root cause is improper handling of serialized data within the plugin's request processing logic. The code passes user-supplied parameters directly to PHP deserialization routines without type checking, allow-listing of permitted classes, or signature verification. CWE-502 (Deserialization of Untrusted Data) applies because the trust boundary between HTTP input and PHP object construction is not enforced.
Attack Vector
The attack is delivered over the network through authenticated WordPress requests targeting plugin endpoints. The attacker submits a serialized PHP object payload via a parameter the plugin later deserializes. Once deserialization occurs, the chained magic methods execute against the constructed object graph, abusing existing class methods to perform unintended operations. See the Patchstack WordPress Vulnerability advisory for additional technical context.
Detection Methods for CVE-2025-46481
Indicators of Compromise
- Inbound HTTP POST or GET parameters containing serialized PHP patterns such as O:, a:, s: followed by length and class name tokens
- Unexpected file creations, modifications, or new PHP files under wp-content/uploads/ or plugin directories
- WordPress audit log entries showing administrative actions invoking Flickr Shortcode Importer endpoints from unusual IP addresses
- Outbound network connections from the web server process to attacker-controlled infrastructure following plugin interaction
Detection Strategies
- Inspect web server and PHP error logs for deserialization warnings, unexpected __wakeup() or __destruct() invocations, and class-not-found errors
- Apply web application firewall rules that flag serialized PHP object signatures in request parameters destined for flickr-shortcode-importer paths
- Monitor file integrity on WordPress directories to detect post-exploitation webshell deployment
Monitoring Recommendations
- Enable verbose logging on the WordPress administrative interface and correlate plugin-related requests with the originating account
- Alert on creation of PHP files in upload directories or modification of theme and plugin files outside scheduled update windows
- Track privileged account logins for anomalous geography, user agents, or session timing patterns
How to Mitigate CVE-2025-46481
Immediate Actions Required
- Deactivate and remove the Flickr Shortcode Importer plugin if a patched version is not available
- Audit all WordPress administrator and editor accounts, rotating credentials and removing inactive privileged users
- Enforce multi-factor authentication on every account capable of reaching plugin endpoints
- Restrict access to /wp-admin/ paths by IP allow-list where operationally feasible
Patch Information
No fixed version is identified in the available references at the time of publication. The plugin is reported vulnerable through version 2.2.3 with no later release noted. Administrators should consult the Patchstack advisory for updates and consider permanent removal of the plugin until a vendor fix is released.
Workarounds
- Uninstall the flickr-shortcode-importer plugin entirely if business processes do not depend on it
- Deploy a WordPress-aware web application firewall with rules blocking serialized PHP payloads in request parameters
- Restrict the PHP runtime using disable_functions in php.ini to limit gadget chains that rely on functions such as exec, system, and file_put_contents
- Run WordPress under a least-privilege filesystem user that cannot modify plugin or theme directories at runtime
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
