CVE-2026-25059 is a path traversal vulnerability classified under CWE-22, found in the OpenList Frontend component of the OpenList product by OpenListTeam. The flaw exists in multiple file operation handlers within the server-side code (server/handles/fsmanage.go), where filename components provided in the request (req.Names) are concatenated with validated directory paths using the standard path join function (stdpath.Join). However, this concatenation does not properly sanitize or normalize the input, allowing attackers to include directory traversal sequences ('..') that bypass directory-level restrictions. As a result, an authenticated attacker can manipulate file paths to access, delete, rename, or copy files belonging to other users within the same storage mount. This breaks the intended authorization boundaries and compromises file system integrity. The vulnerability has a CVSS 3.1 score of 8.8, indicating high severity, with network attack vector, low attack complexity, requiring privileges (authenticated user), no user interaction, and impacts confidentiality, integrity, and availability. The issue was resolved in OpenList version 4.1.10 by properly validating and sanitizing filename inputs to prevent traversal sequences from escaping restricted directories.

For European organizations using OpenList versions prior to 4.1.10, this vulnerability poses significant risks. Unauthorized file access and manipulation can lead to data breaches, loss of sensitive information, and disruption of services relying on file integrity. Since the vulnerability allows attackers to delete or rename files, it can cause denial of service conditions or data loss. Confidentiality is compromised as attackers can access files of other users, potentially exposing personal or business-critical data. Integrity is affected by unauthorized modifications, and availability is threatened by deletion or corruption of files. Organizations in sectors with strict data protection regulations, such as GDPR, face legal and compliance risks if exploited. The requirement for authentication limits exposure but insider threats or compromised credentials can still lead to exploitation. The lack of known exploits in the wild currently reduces immediate risk but patching is critical to prevent future attacks.

European organizations should immediately upgrade OpenList to version 4.1.10 or later, where the vulnerability is fixed. Until patching is possible, implement strict access controls and monitoring on OpenList storage mounts to detect unusual file operations. Employ application-layer firewalls or runtime application self-protection (RASP) tools to detect and block path traversal patterns in requests. Conduct thorough audits of user permissions and review authentication mechanisms to reduce risk from compromised accounts. Implement logging and alerting for file operations that involve deletion, renaming, or copying across user boundaries. Educate users about credential security to prevent unauthorized access. Additionally, consider isolating storage mounts per user or group to limit the blast radius of potential exploitation. Regularly review and test the application for similar input validation issues to prevent recurrence.