CVE-2019-16983 in FusionPBX
Summary
by MITRE
In FusionPBX up to v4.5.7, the file resources\paging.php has a paging function (called by several pages of the interface), which uses an unsanitized "param" variable constructed partially from the URL args and reflected in HTML, leading to XSS.
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Analysis
by VulDB Data Team • 01/17/2024
The vulnerability identified as CVE-2019-16983 affects FusionPBX versions up to v4.5.7 and resides within the file resources/paging.php. This represents a classic cross-site scripting vulnerability that exploits improper input validation mechanisms within the application's paging functionality. The vulnerability manifests when the application processes URL parameters without adequate sanitization, creating an attack surface where malicious actors can inject arbitrary JavaScript code through the param variable.
The technical flaw stems from the application's failure to properly sanitize user-supplied input within the paging function that is invoked across multiple interface pages. When URL arguments are passed to the param variable, the application directly incorporates these values into HTML output without appropriate encoding or validation. This unsanitized input allows attackers to construct malicious payloads that execute within the context of other users' browsers, leveraging the reflected nature of the vulnerability where the injected code is immediately reflected back to the user.
The operational impact of this vulnerability extends beyond simple script execution as it provides attackers with the ability to hijack user sessions, steal sensitive information, or perform unauthorized actions within the application's context. Given that the paging function is called by several interface pages, the attack surface is broadened, potentially affecting multiple user interactions throughout the FusionPBX application. The reflected nature of the vulnerability means that successful exploitation requires social engineering to trick users into clicking malicious links, making it particularly dangerous in targeted attack scenarios.
From a security standards perspective, this vulnerability maps directly to CWE-79 - Cross-site Scripting and aligns with ATT&CK technique T1566.001 - Phishing: Spearphishing Attachment. The vulnerability demonstrates poor input validation practices that violate secure coding principles and application security best practices. Organizations using FusionPBX versions prior to v4.5.8 should immediately implement mitigations including input sanitization, output encoding, and proper parameter validation. The recommended remediation involves implementing strict input validation for all URL parameters and ensuring that any user-supplied data is properly escaped before being rendered in HTML contexts. Additionally, implementing Content Security Policy headers and using secure coding practices such as parameterized queries and input sanitization can significantly reduce the risk of exploitation. Regular security assessments and code reviews should be conducted to identify similar vulnerabilities in other application components and ensure comprehensive protection against similar cross-site scripting threats.