CVE-2025-49125 is an authentication bypass vulnerability classified under CWE-288, discovered in the Apache Software Foundation's Apache Tomcat server. The issue occurs when PreResources or PostResources are mounted at locations other than the root of a web application. These resources can then be accessed via an alternate, unexpected path that is not protected by the same security constraints as the intended path. This discrepancy allows attackers to circumvent authentication mechanisms and gain unauthorized access to sensitive resources. The vulnerability affects multiple Tomcat versions, specifically from 8.5.0 through 8.5.100 (EOL but affected), 9.0.0.M1 through 9.0.105, 10.1.0-M1 through 10.1.41, and 11.0.0-M1 through 11.0.7. The flaw does not require any privileges or user interaction to exploit and can be triggered remotely over the network. The CVSS v3.1 base score is 7.5, reflecting a high severity due to the potential for unauthorized data disclosure. The vulnerability impacts confidentiality but does not affect integrity or availability. No public exploits have been reported yet, but the nature of the flaw suggests it could be leveraged to access sensitive information or internal application resources that should be protected. The Apache Software Foundation has released fixed versions 11.0.8, 10.1.42, and 9.0.106 to address this issue. Organizations using affected versions should prioritize upgrading and review their resource mounting configurations to ensure security constraints are consistently applied.

For European organizations, the impact of CVE-2025-49125 is significant due to the widespread use of Apache Tomcat in enterprise, government, and critical infrastructure environments. Unauthorized access to protected resources can lead to exposure of sensitive data, including personal information, intellectual property, or internal application logic, potentially violating GDPR and other data protection regulations. The confidentiality breach could damage organizational reputation, result in regulatory fines, and facilitate further attacks such as data exfiltration or lateral movement within networks. Since the vulnerability does not affect integrity or availability, direct system disruption is unlikely; however, the loss of confidentiality alone is critical. The ease of remote exploitation without authentication increases the risk of automated scanning and attacks. European sectors with high reliance on Tomcat for web services, such as finance, healthcare, public administration, and telecommunications, are particularly vulnerable. The vulnerability also poses risks to cloud-hosted applications and managed services operating within Europe, where compliance and data sovereignty are paramount.

The primary mitigation is to upgrade Apache Tomcat to the fixed versions 11.0.8, 10.1.42, or 9.0.106 as soon as possible. Organizations should audit their web applications to identify any use of PreResources or PostResources mounted at non-root paths and verify that security constraints are correctly applied to all resource paths. Implement strict access control policies and consider additional application-layer protections such as Web Application Firewalls (WAFs) configured to detect and block unusual path traversal attempts. Conduct thorough penetration testing and code reviews focusing on resource mounting and access control configurations. Monitor network traffic and logs for anomalous access patterns that may indicate exploitation attempts. For environments where immediate upgrade is not feasible, consider isolating vulnerable Tomcat instances behind network segmentation and restricting access to trusted users only. Maintain up-to-date backups and incident response plans to quickly address any potential breaches resulting from exploitation.