InvoicePlane is an open-source web-based invoicing application used by small businesses and freelancers to manage their billing processes. The software allows users to create and manage invoices, quotes, clients, payments, and more, providing a comprehensive set of tools for financial management. InvoicePlane is deployed on a variety of web servers, integrating with multiple payment platforms to provide seamless transaction handling and invoicing services. Its community-driven development ensures continuous enhancements and security updates, which are crucial for the sensitive financial data it handles. Commonly deployed in a PHP environment, it is typically used in hosted scenarios where it needs to be secure against external threats. Ensuring uptime and data integrity are high priorities for its user base to maintain financial operations smoothly.
The Arbitrary File Read vulnerability in InvoicePlane, identified as CVE-2026-23491, allows unauthenticated attackers to potentially read files outside the intended directory. This vulnerability occurs due to insufficient validation of the file path in the application's path traversal logic, specifically in the "Get::get_file()" controller. By exploiting this flaw, an attacker could access sensitive files such as configuration files that contain database credentials and encryption keys. This vulnerability remains present in versions up to 1.6.3. Fortunately, the vulnerability was mitigated by introducing a helper function in version 1.6.4 that ensures proper file access validation.
Technical details indicate that the vulnerable endpoint is "/index.php/guest/get/get_file/" and the parameter accepting the file path is inadequately validated against directory traversal attacks. Using a crafted URL containing encoded directory traversal sequences like "%2f%2f../" within the filename parameter, attackers can bypass controls and access restricted files. The use of functions like urldecode() without sufficient sanitization leads to this vulnerability. The vulnerable code allows an arbitrary file to be retrieved, as demonstrated by accessing "ipconfig.php", revealing critical configuration information. The introduction of robust file validation in later versions addresses these flaws, preventing unauthorized file access.
If exploited, this vulnerability could lead to the exposure of sensitive information, such as database credentials or encryption keys, that are critical for maintaining data integrity and confidentiality. Attackers could leverage this access to further compromise the system, potentially accessing or manipulating protected data. Organizations using vulnerable versions of InvoicePlane are at risk of unauthorized data breaches, leading to financial loss and reputational damage. Securing the application against such intrusions is essential to safeguarding the confidentiality and availability of financial data managed by InvoicePlane.
REFERENCES
- Upgrade InvoicePlane to version 1.6.4 or later, as these versions include patches that resolve the Arbitrary File Read vulnerability.
- Implement strict input validation and sanitization on all file path inputs to prevent unauthorized access.
- Employ a robust access control mechanism that restricts file access only to authenticated and authorized users.
- Regularly review and update your application's security settings and configurations as guided by best practices.
- Consider using web application firewalls to detect and block suspicious activities related to path traversal attacks.
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