CVE-2025-53586: 
WordPress vulnerability analysis and mitigation

CVE-2025-53586 is a PHP Object Injection vulnerability (Deserialization of Untrusted Data) in the NooTheme WeMusic WordPress theme, affecting all versions up to and including 1.9.1. The flaw allows a low-privileged authenticated attacker to inject arbitrary PHP objects via deserialization, potentially leading to remote code execution if a suitable POP (Property-Oriented Programming) chain exists. It was reported by Tran Nguyen Bao Khanh (VCI - VNPT Cyber Immunity) on July 3, 2025, and published by Patchstack on August 2, 2025. The CVE was formally published on November 6, 2025, with a CVSS v3.1 base score of 8.8 (High) (Patchstack).

The vulnerability is classified as CWE-502 (Deserialization of Untrusted Data) and is mapped to CAPEC-586 (Object Injection). The root cause is the WeMusic theme's failure to safely handle serialized PHP data supplied by low-privileged users (Subscriber-level or above), allowing attackers to pass crafted serialized payloads that are deserialized without proper validation. If a suitable POP chain is available within the WordPress environment (e.g., via installed plugins or themes), this can be escalated to remote code execution, SQL injection, path traversal, or denial of service. The attack is network-based, requires low privileges, and no user interaction (Patchstack).

Successful exploitation grants an attacker high impact across confidentiality, integrity, and availability of the affected WordPress installation. Depending on available POP chains in the environment, consequences can include remote code execution, unauthorized data access, database manipulation, file system traversal, and complete site compromise. The network-based attack vector with no user interaction required makes this particularly dangerous for internet-facing WordPress sites running the vulnerable theme (Patchstack).

As of the time of publication, there is no public proof-of-concept exploit and no evidence of active in-the-wild exploitation. The EPSS score is approximately 0.024% (0.000240), indicating a currently low probability of exploitation in the near term. No threat actor attribution has been reported, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. However, Patchstack classifies it as high priority, noting that vulnerabilities of this class are frequently used in mass-exploit campaigns targeting WordPress sites (Patchstack).

1. Reconnaissance: Identify WordPress sites running the NooTheme WeMusic theme at version 1.9.1 or earlier using tools like WPScan, Shodan, or manual HTTP fingerprinting of theme assets.
2. Obtain low-privileged access: Register or obtain a Subscriber-level (or higher) account on the target WordPress site, as the vulnerability requires authenticated access.
3. Identify the vulnerable deserialization endpoint: Locate the theme functionality that accepts and deserializes user-supplied data (e.g., a form field, AJAX handler, or REST API endpoint within the WeMusic theme).
4. Craft a malicious serialized payload: Using a tool such as PHPGGC, generate a PHP serialized object payload targeting a POP chain available in the WordPress environment (e.g., from installed plugins or WordPress core).
5. Submit the payload: Send the crafted serialized payload to the vulnerable endpoint via an authenticated HTTP request.
6. Achieve objective: If a valid POP chain is present, the deserialized object triggers arbitrary code execution, file write, SQL injection, or other malicious actions on the server (Patchstack).

• Network: Unusual authenticated POST or GET requests to WeMusic theme AJAX handlers or REST endpoints containing serialized PHP data (strings beginning with O:, a:, s: patterns in request bodies or parameters).
• Logs: WordPress access logs showing repeated requests from a single low-privileged user account to theme-specific endpoints; PHP error logs referencing unexpected class instantiation or unserialize() calls.
• File System: Unexpected PHP files or web shells created in the WordPress uploads directory or theme directory; modification timestamps on core WordPress files inconsistent with legitimate updates.
• Process: Unusual child processes spawned by the web server process (e.g., bash, curl, wget, python) following web requests to the WordPress installation.

The vendor has released WeMusic version 1.9.2 as the patched release; all users should upgrade immediately from versions 1.9.1 and below. Patchstack has also issued a virtual patch (mitigation rule) for subscribers of its service to block exploitation attempts until the theme is updated. As additional hardening measures, restrict WordPress user registration if not required, implement a Web Application Firewall (WAF) to detect and block suspicious deserialization payloads, and monitor WordPress logs for anomalous serialized data in requests (Patchstack).

The vulnerability was discovered and responsibly disclosed by Tran Nguyen Bao Khanh of VCI - VNPT Cyber Immunity, with Patchstack coordinating the disclosure and issuing a virtual patch. Patchstack categorizes this as a high-priority vulnerability, warning that PHP Object Injection flaws of this type are commonly leveraged in mass-exploit campaigns against WordPress sites. No significant broader media coverage or notable social media discussion has been identified beyond the Patchstack advisory (Patchstack).