Description

Unauthenticated PHP Object Injection in Mail Mint <= 1.31.0 versions.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-09-03T17:17:25.673Z",
  "pubdate": "2026-09-03T17:17:25.673Z",
  "executiveSummary": "Mail Mint versions 1.31.0 and earlier contain a critical PHP Object Injection vulnerability. This flaw allows an unauthenticated remote attacker to inject serialized PHP objects into the application, potentially leading to Remote Code Execution (RCE), arbitrary file deletion, or sensitive data disclosure.\nThe vulnerability stems from the insecure deserialization of user-supplied input. By crafting a malicious serialized payload, an attacker can manipulate the application's internal object state or trigger unintended execution flows within the context of the web server process.\nGiven that the vulnerability does not require authentication, the risk is severe. Successful exploitation provides the attacker with a foothold on the server, potentially leading to a total system compromise depending on the available PHP 'gadget chains' present within the application's codebase or its environment.\nAffected organizations should treat this as a high-priority security issue, as it allows for unauthorized interaction with the application's underlying logic without valid credentials.",
  "technicalDetails": "The vulnerability resides in the way Mail Mint handles serialized data from user requests. PHP Object Injection occurs when an application calls the unserialize() function on untrusted input without proper validation or integrity checks. In Mail Mint <= 1.31.0, an attacker can supply a specially crafted serialized string that is processed by the vulnerable component.\nRoot Cause: The insecure use of unserialize() on data controlled by the user allows an attacker to instantiate objects of arbitrary classes available in the application scope. By leveraging existing 'gadget chains'—sequences of class methods (such as __destruct, __wakeup, or __toString) that perform dangerous operations—an attacker can execute arbitrary code or manipulate file systems.\nAttack Flow: 1. Identification of an endpoint in Mail Mint that accepts serialized data as part of a POST or GET request. 2. Construction of a malicious PHP payload using a gadget chain found within the application or its bundled third-party libraries. 3. Transmission of the serialized object to the vulnerable endpoint via HTTP. 4. Upon invocation of unserialize(), the application populates the properties of the injected object and triggers the magic methods associated with the gadget chain.\nExploitation Requirements: The attacker does not need authentication to trigger this process. The vulnerability is network-exposed, making it accessible from any external source capable of reaching the web server. The post-exploitation impact is limited only by the permissions of the web server user (typically www-data) and the presence of accessible gadget chains.\nTechnical Impact: If a suitable gadget chain is identified, the attacker can achieve Remote Code Execution. This allows the attacker to install backdoors, pivot through the internal network, exfiltrate the WordPress database (including user credentials and customer data), or modify site content. The lack of input sanitization at the entry point is the fundamental failure point in the Mail Mint architecture, allowing for this direct manipulation of object instantiation."
}