CVE-2025-54366 in freescout
Summary
by MITRE • 07/26/2025
FreeScout is a lightweight free open source help desk and shared inbox built with PHP (Laravel framework). In versions 1.8.185 and below, there is a critical deserialization vulnerability in the /conversation/ajax endpoint that allows authenticated users with knowledge of the APP_KEY to achieve remote code execution. The vulnerability occurs when the application processes the attachments_all and attachments POST parameters through the insecure Helper::decrypt() function, which performs unsafe deserialization of user-controlled data without proper validation. This flaw enables attackers to create arbitrary objects and manipulate their properties, leading to complete compromise of the web application. This is fixed in version 1.8.186.
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Analysis
by VulDB Data Team • 09/11/2025
The CVE-2025-54366 vulnerability represents a critical remote code execution flaw in FreeScout versions 1.8.185 and earlier, exploiting a dangerous deserialization weakness in the application's conversation handling mechanism. This open source help desk software, built on the PHP Laravel framework, contains a fundamental security flaw in its /conversation/ajax endpoint that directly compromises system integrity when exploited by authenticated users. The vulnerability specifically targets the Helper::decrypt() function which processes user-supplied attachment data without adequate input validation, creating a dangerous attack surface that allows for arbitrary object manipulation and code execution.
The technical exploitation of this vulnerability occurs through the manipulation of POST parameters named attachments_all and attachments which are processed through the insecure Helper::decrypt() function. This function performs unsafe deserialization operations on user-controlled data, allowing attackers to craft malicious serialized objects that, when processed, can execute arbitrary PHP code on the target system. The vulnerability requires an authenticated user with knowledge of the application's APP_KEY, which serves as the cryptographic key for encryption and decryption operations within the Laravel framework. This requirement significantly reduces the attack surface but does not eliminate the critical nature of the flaw, as authenticated access often provides sufficient privileges to cause substantial damage. The flaw aligns with CWE-502, which specifically addresses unsafe deserialization vulnerabilities where untrusted data is deserialized without proper validation, and can be mapped to ATT&CK technique T1059.007 for scripting languages and T1566 for phishing with malicious attachments.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise, as the attacker gains the ability to manipulate the application's underlying functionality and potentially escalate privileges within the system. The deserialization process enables attackers to create arbitrary objects with malicious properties, potentially allowing them to execute commands, access sensitive data, or modify the application's behavior. Given that FreeScout operates as a help desk and shared inbox solution, successful exploitation could lead to unauthorized access to confidential communications, user data breaches, and potential lateral movement within the network. The vulnerability's severity is amplified by the fact that it requires only authenticated access and knowledge of the APP_KEY, which may be obtained through various means including credential theft or prior compromise of the system. Organizations using affected versions should immediately implement mitigation strategies including patching to version 1.8.186, monitoring for suspicious activity in the conversation endpoints, and reviewing authentication controls to prevent unauthorized access to the application's administrative functions.
The exploitation chain begins with an authenticated user leveraging their access privileges to submit maliciously crafted data through the /conversation/ajax endpoint, specifically targeting the attachments_all and attachments parameters. The Helper::decrypt() function processes this data without proper validation, allowing attackers to inject serialized objects that, when deserialized, execute arbitrary code on the server. This vulnerability demonstrates the critical importance of input validation and secure deserialization practices in web applications, particularly those built on frameworks like Laravel that handle encryption and decryption operations. The fix in version 1.8.186 addresses the core issue by implementing proper validation and sanitization of user-controlled data before deserialization occurs, following security best practices recommended by organizations such as OWASP and NIST for preventing similar vulnerabilities in PHP applications.