CVE-2025-54021 is a high-severity path traversal vulnerability (CWE-22) found in the Simple File List product developed by Mitchell Bennis. This vulnerability allows an attacker to manipulate file path inputs to access files and directories outside the intended restricted directory. Specifically, the flaw arises from improper limitation of pathname inputs, enabling traversal sequences such as '../' to escape the designated directory boundaries. The affected versions include all versions up to 6.1.14, with no specific earliest version identified. The vulnerability has a CVSS 3.1 base score of 7.5, indicating a high severity level. The CVSS vector (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) shows that the attack can be performed remotely over the network without any privileges or user interaction, and it impacts confidentiality with high impact but does not affect integrity or availability. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability could allow attackers to read sensitive files on the server hosting the Simple File List application, potentially exposing confidential data such as configuration files, credentials, or other sensitive documents stored outside the intended file list directory. This can lead to significant data breaches and privacy violations if exploited.

For European organizations using Simple File List, this vulnerability poses a significant risk to the confidentiality of sensitive data. Since the exploit requires no authentication or user interaction, attackers can remotely access sensitive files, potentially exposing personal data protected under GDPR, intellectual property, or internal business documents. This could lead to regulatory penalties, reputational damage, and financial losses. Organizations in sectors such as finance, healthcare, government, and critical infrastructure that rely on Simple File List for document management or file sharing are particularly at risk. The ability to access files outside the intended directory could also facilitate further attacks by revealing system configurations or credentials. Given the lack of known exploits in the wild, the threat is currently theoretical but could escalate rapidly once exploit code becomes available. The vulnerability's network accessibility and ease of exploitation increase the urgency for European entities to assess and remediate this issue promptly.

1. Immediate mitigation should include restricting network access to the Simple File List application to trusted IP addresses or VPNs to reduce exposure. 2. Monitor web server logs for suspicious requests containing path traversal patterns such as '../' sequences. 3. Implement web application firewall (WAF) rules that detect and block path traversal attempts targeting the affected endpoints. 4. Until an official patch is released, consider deploying virtual patching techniques via WAF or reverse proxies to sanitize input paths. 5. Review and harden file system permissions to ensure the web server user has minimal access rights outside the intended directories, limiting the impact of any traversal. 6. Regularly check for updates from Mitchell Bennis and apply patches as soon as they become available. 7. Conduct security audits and penetration testing focused on file access controls within the Simple File List environment. 8. Educate system administrators about this vulnerability and the importance of timely patching and monitoring.