CVE-2025-65799 identifies a path traversal vulnerability in the Attachment service component of usememos memos version 0.25.2. The root cause is the absence of proper validation or verification of file names submitted during attachment uploads or handling. This deficiency enables an attacker to craft malicious file paths containing traversal sequences (e.g., '../') that bypass intended directory restrictions. By exploiting this, an attacker can access files outside the designated attachment directory, potentially reading sensitive files or overwriting critical system or application files. The vulnerability does not require authentication or user interaction, increasing its risk profile. Although no CVSS score or patches are currently available, the flaw is publicly disclosed and reserved under CVE-2025-65799. No known exploits have been observed in the wild yet. The lack of file name sanitization is a common security oversight that can lead to severe consequences including data breaches, privilege escalation, or denial of service if critical files are tampered with. The affected software, usememos memos, is a note-taking and collaboration tool, which may be deployed in enterprise or organizational environments. Without mitigations, attackers could leverage this vulnerability to compromise confidentiality and integrity of data stored on affected servers.

For European organizations, exploitation of this vulnerability could result in unauthorized access to sensitive internal documents, intellectual property, or personal data, violating GDPR and other data protection regulations. The integrity of organizational data could be compromised if attackers overwrite or delete files, potentially disrupting business operations or causing data loss. Availability may also be affected if critical system files are altered, leading to service outages. Organizations using usememos memos in sectors such as finance, healthcare, or government are particularly at risk due to the sensitivity of their data. The lack of authentication requirement means that any attacker with network access to the application could attempt exploitation, increasing the attack surface. This vulnerability could also serve as a foothold for further lateral movement within networks. The reputational damage and regulatory penalties from a successful attack could be significant for European entities.

Immediate mitigation involves implementing strict validation and sanitization of all file names and paths in the Attachment service to prevent traversal sequences. This includes rejecting or neutralizing characters such as '../' or absolute path indicators. Organizations should monitor and restrict file upload functionality to trusted users and networks where possible. Employing web application firewalls (WAFs) with rules to detect and block path traversal attempts can provide temporary protection. Regularly auditing file system permissions to ensure the application runs with least privilege limits the impact of potential exploitation. Until an official patch is released, consider isolating the usememos memos service in a sandboxed environment or container to reduce risk. Monitoring logs for unusual file access patterns or errors related to attachments can help detect exploitation attempts early. Finally, organizations should maintain an inventory of affected software versions and plan for timely updates once patches become available.