CVE-2026-25869 is a path traversal vulnerability identified in MiniGal Nano, a lightweight PHP-based web photo gallery application. The flaw exists in the index.php file where the 'dir' parameter is used to specify subdirectories within the photos directory. The application attempts to prevent directory traversal attacks by removing dot-dot ('..') sequences from user input. However, this sanitization is insufficient and can be bypassed using crafted directory patterns that evade the simplistic filtering logic. As a result, an attacker can manipulate the 'dir' parameter to traverse outside the intended photos directory and access arbitrary filesystem locations readable by the web server. This leads to unintended information disclosure, as the application enumerates and displays image files from these unauthorized directories. The vulnerability requires no authentication or user interaction and can be exploited remotely over the network. The CVSS 4.0 vector indicates low complexity, no privileges required, no user interaction, and limited confidentiality impact, with no effect on integrity or availability. No patches or known exploits are currently available, but the vulnerability poses a risk of sensitive information leakage if the web server has access to confidential image files or directories. Organizations using MiniGal Nano versions 0.3.5 or earlier should consider this vulnerability in their risk assessments.

For European organizations, the primary impact of this vulnerability is unintended information disclosure. If MiniGal Nano is deployed in environments where sensitive images or files reside on the same server or accessible directories, attackers could gain access to confidential data. This could include personal data protected under GDPR, intellectual property, or internal documentation stored as images. Although the vulnerability does not allow code execution or modification of files, the exposure of sensitive information can lead to reputational damage, regulatory penalties, and further targeted attacks. The ease of exploitation without authentication increases the risk, especially for publicly accessible web galleries. Organizations in sectors such as media, education, healthcare, or government that use MiniGal Nano for image hosting should be particularly cautious. The lack of known exploits reduces immediate threat but does not eliminate risk, as attackers could develop exploits given the public disclosure. The medium severity rating reflects moderate risk but should not lead to complacency given the potential data privacy implications under European regulations.

Since no official patches are currently available, organizations should implement the following mitigations: 1) Immediately restrict access to the MiniGal Nano application to trusted networks or authenticated users to reduce exposure. 2) Employ web application firewalls (WAFs) with custom rules to detect and block suspicious directory traversal patterns in the 'dir' parameter, including encoded or obfuscated variants. 3) Review and harden web server file permissions to ensure the web server user has minimal read access only to necessary directories, preventing access to sensitive files outside the photos directory. 4) Consider disabling or removing the vulnerable 'dir' parameter functionality if feasible or replacing MiniGal Nano with a more secure alternative. 5) Monitor web server logs for unusual requests targeting the 'dir' parameter or attempts to access unexpected directories. 6) Once patches become available, prioritize timely application. 7) Conduct security awareness and training for administrators managing MiniGal Nano deployments to recognize and respond to exploitation attempts. These steps go beyond generic advice by focusing on access control, input filtering, and operational monitoring tailored to this vulnerability's exploitation method.