CVE-2025-49455: TinySalt Object Injection Vulnerability

CVE-2025-49455 Overview

CVE-2025-49455 is a critical Insecure Deserialization vulnerability affecting the LoftOcean TinySalt WordPress theme. The vulnerability allows attackers to perform PHP Object Injection attacks through deserialization of untrusted data. This issue affects all versions of TinySalt prior to version 3.10.0.

PHP Object Injection vulnerabilities occur when user-controllable input is passed to the unserialize() function without proper validation. When exploited, attackers can inject arbitrary PHP objects that may trigger dangerous "magic methods" during deserialization, potentially leading to remote code execution, file manipulation, or data exfiltration.

Critical Impact

Unauthenticated attackers can exploit this vulnerability to inject malicious PHP objects, potentially achieving remote code execution on vulnerable WordPress installations running TinySalt theme versions prior to 3.10.0.

Affected Products

• LoftOcean TinySalt WordPress theme versions prior to 3.10.0

Discovery Timeline

• 2025-06-10 - CVE CVE-2025-49455 published to NVD
• 2025-06-12 - Last updated in NVD database

Technical Details for CVE-2025-49455

Vulnerability Analysis

This vulnerability stems from improper handling of serialized data within the TinySalt WordPress theme. The application deserializes user-supplied input without adequate validation, enabling attackers to craft malicious serialized payloads containing arbitrary PHP objects.

When the vulnerable code processes this malicious input, PHP instantiates the injected objects and automatically invokes magic methods such as __wakeup(), __destruct(), or __toString(). If the codebase or any loaded libraries contain classes with dangerous implementations of these magic methods (known as "gadget chains"), the attacker can chain these gadgets together to achieve arbitrary code execution.

The network-accessible nature of this vulnerability, combined with the lack of authentication requirements, makes it particularly dangerous for WordPress sites using the affected theme.

Root Cause

The root cause is CWE-502: Deserialization of Untrusted Data. The TinySalt theme accepts serialized PHP data from untrusted sources and passes it to deserialization functions without proper input validation or sanitization. This violates secure coding practices that dictate user-controlled data should never be directly deserialized.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker can remotely send crafted HTTP requests containing malicious serialized PHP payloads to the vulnerable WordPress installation. The serialized payload is designed to instantiate PHP objects that, when combined with existing classes in the WordPress ecosystem, can execute arbitrary code.

The exploitation typically follows this pattern:

1. Attacker identifies a WordPress site running a vulnerable version of TinySalt
2. Attacker crafts a malicious serialized PHP object leveraging known gadget chains
3. The payload is delivered via an HTTP request to an endpoint processing serialized data
4. Upon deserialization, magic methods are triggered, executing the attacker's payload

For detailed technical information about this vulnerability, refer to the Patchstack Security Advisory.

Detection Methods for CVE-2025-49455

Indicators of Compromise

• Unusual HTTP requests containing serialized PHP data patterns (e.g., O: followed by class names and parameters)
• Web server logs showing requests with base64-encoded or URL-encoded serialized objects
• Unexpected file modifications or new files created in WordPress directories
• Anomalous outbound network connections from the web server

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect and block serialized PHP object patterns in HTTP requests
• Implement monitoring for suspicious strings in request parameters such as O:, a:, s: which indicate PHP serialization
• Use SentinelOne Singularity Platform for real-time detection of exploitation attempts and post-exploitation activities
• Enable WordPress security plugins that can detect object injection attempts

Monitoring Recommendations

• Monitor web server access logs for requests containing unusual serialized data patterns
• Implement file integrity monitoring on WordPress core, theme, and plugin directories
• Set up alerting for unexpected PHP process spawning or command execution
• Review server logs for signs of reverse shell connections or data exfiltration attempts

How to Mitigate CVE-2025-49455

Immediate Actions Required

• Update TinySalt theme to version 3.10.0 or later immediately
• Audit WordPress installations to identify all instances running vulnerable TinySalt versions
• Review web server logs for evidence of exploitation attempts prior to patching
• Consider temporarily disabling the TinySalt theme on critical sites until patching is complete

Patch Information

LoftOcean has addressed this vulnerability in TinySalt version 3.10.0. Site administrators should update to this version or later through the WordPress theme update mechanism or by downloading the patched version from the theme provider.

For additional patch details, refer to the Patchstack Security Advisory.

Workarounds

• Implement WAF rules to block requests containing serialized PHP object patterns until patching is feasible
• Restrict access to the WordPress admin panel and theme-related endpoints to trusted IP addresses
• Enable WordPress security plugins with object injection detection capabilities
• Consider placing the site in maintenance mode if the risk is deemed too high and immediate patching is not possible

# WAF rule example for ModSecurity to block PHP object injection attempts
SecRule REQUEST_BODY "@rx O:\d+:\"[^\"]+\":\d+:{" \
    "id:100001,\
    phase:2,\
    deny,\
    status:403,\
    msg:'PHP Object Injection Attempt Blocked',\
    severity:CRITICAL"