CVE-2025-49438 Overview
CVE-2025-49438 is a PHP Object Injection vulnerability affecting the Max Chirkov Simple Login Log WordPress plugin in versions up to and including 1.1.3. The flaw stems from deserialization of untrusted data [CWE-502], which allows an attacker to inject crafted serialized PHP objects into the application. Successful exploitation can compromise confidentiality, integrity, and availability of the affected WordPress site. The vulnerability is reachable over the network without authentication, though exploitation requires high attack complexity.
Critical Impact
Unauthenticated attackers can inject malicious PHP objects into Simple Login Log 1.1.3 and earlier, potentially leading to arbitrary code execution when a suitable POP chain is present.
Affected Products
- Max Chirkov Simple Login Log plugin for WordPress
- All versions from n/a through 1.1.3
- WordPress sites with the vulnerable plugin installed and activated
Discovery Timeline
- 2025-08-20 - CVE-2025-49438 published to NVD
- 2026-04-28 - Last updated in NVD database
Technical Details for CVE-2025-49438
Vulnerability Analysis
The Simple Login Log plugin processes serialized data with PHP's unserialize() function without validating the source or content of that data. When attacker-controlled input reaches the deserialization routine, PHP reconstructs arbitrary object instances and invokes magic methods such as __wakeup(), __destruct(), or __toString() during object lifecycle events. If the WordPress environment loads classes that define exploitable magic methods, an attacker can chain those gadgets into a Property-Oriented Programming (POP) sequence. The end result can include arbitrary file writes, SQL injection, or remote code execution depending on the available gadget chain.
Root Cause
The root cause is unsafe deserialization of attacker-controlled input within the plugin's logging functionality. The code path accepts serialized PHP data and passes it to unserialize() without using safe alternatives such as json_decode() or the allowed_classes option introduced in PHP 7. This pattern is the canonical CWE-502 weakness.
Attack Vector
The vulnerability is exploitable over the network without authentication or user interaction. An attacker crafts a serialized PHP payload representing a class instance available in the WordPress runtime, then delivers it through a request channel processed by Simple Login Log. The high attack complexity reflects the dependency on a usable POP gadget chain within the target WordPress installation, including its themes and other active plugins. Sites that load common libraries known to contain gadget chains face increased risk.
No public proof-of-concept code is currently available. See the Patchstack advisory for additional technical context.
Detection Methods for CVE-2025-49438
Indicators of Compromise
- HTTP request bodies or parameters containing serialized PHP markers such as O:, a:, or s: followed by class names and lengths
- Unexpected PHP errors referencing __wakeup, __destruct, or unserialize() in web server logs
- New or modified PHP files in the WordPress wp-content directory following suspicious requests to the plugin's endpoints
- Outbound network connections originating from the PHP worker process after requests targeting Simple Login Log
Detection Strategies
- Inspect web server access logs for requests to Simple Login Log endpoints containing serialized object patterns matching the regex O:\d+:"[^"]+":\d+:
- Deploy a web application firewall ruleset that flags PHP serialization syntax in untrusted inputs
- Monitor file integrity on the WordPress installation, focusing on plugin and uploads directories
Monitoring Recommendations
- Enable PHP error logging and forward logs to a centralized analytics platform for correlation
- Alert on creation of PHP files in writable WordPress directories such as wp-content/uploads
- Track administrator account creation, role changes, and option modifications in the wp_options table for anomalous activity
How to Mitigate CVE-2025-49438
Immediate Actions Required
- Identify all WordPress installations running Simple Login Log version 1.1.3 or earlier
- Deactivate and remove the plugin if a patched version is not available for your environment
- Restrict administrative access and review login logs for unauthorized activity
- Apply web application firewall rules to block requests containing PHP serialization payloads
Patch Information
No fixed version is referenced in the public advisory at the time of writing. Review the Patchstack advisory for updates on a vendor patch. If no patched release is published, replace the plugin with an actively maintained alternative.
Workarounds
- Remove Simple Login Log until a patched version is confirmed available
- Place the WordPress site behind a web application firewall with rules that block serialized PHP object patterns in request data
- Run PHP with the lowest viable privilege and restrict write permissions on plugin and theme directories
- Audit installed plugins and themes to reduce the pool of classes available for POP gadget chains
# Configuration example: WAF rule fragment to block PHP serialized objects in request bodies
SecRule REQUEST_BODY "@rx O:[0-9]+:\"[A-Za-z_\\\\]+\":[0-9]+:" \
"id:1004943,phase:2,deny,status:403,log,msg:'Possible PHP object injection payload'"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
