CVE-2025-54656 is a vulnerability classified under CWE-117, which pertains to improper output neutralization for logs, affecting the Apache Software Foundation's Apache Struts Extras component. Specifically, this vulnerability exists in versions prior to 2 of Apache Struts Extras, a project that has since been retired and is no longer supported. The issue arises when using the LookupDispatchAction feature, where Struts may log untrusted input without adequate filtering or sanitization. This improper handling allows specially crafted input to manipulate log entries, causing parts of a single log message to appear as separate log lines. Such log injection can mislead both human operators and automated log analysis tools, potentially obscuring malicious activity or causing confusion during incident response. Since the project is retired, no patches or fixes will be released, and users are advised to migrate to alternative solutions or restrict access to trusted users only. The vulnerability does not have any known exploits in the wild as of the publication date, and no CVSS score has been assigned.

For European organizations, this vulnerability poses a risk primarily to the integrity and reliability of log data, which is critical for security monitoring, auditing, and forensic investigations. If exploited, attackers could inject misleading entries into logs, potentially hiding their tracks or triggering false alarms. This can delay detection of breaches or complicate incident response efforts. While the vulnerability does not directly lead to remote code execution or data leakage, the manipulation of logs undermines trust in security controls and can facilitate more sophisticated attacks by masking malicious activity. Organizations relying on Apache Struts Extras, especially legacy systems that have not migrated away from this retired project, are at risk. Given the lack of vendor support, these organizations face increased operational risk and compliance challenges, particularly under European data protection regulations that mandate accurate logging and monitoring.

Since no patches are forthcoming due to the retirement of the Apache Struts Extras project, European organizations should prioritize the following mitigations: 1) Immediate migration away from Apache Struts Extras to supported and actively maintained frameworks or libraries to eliminate exposure. 2) If migration is not immediately feasible, restrict access to affected systems strictly to trusted and authenticated users, ideally within isolated network segments with strong access controls and monitoring. 3) Implement log integrity verification mechanisms such as cryptographic signing or append-only logging to detect tampering or injection attempts. 4) Enhance log monitoring and anomaly detection capabilities to identify suspicious log patterns indicative of injection or manipulation. 5) Conduct regular security audits and penetration testing focused on legacy systems to identify and remediate related risks. 6) Educate incident response teams about the potential for log manipulation to ensure careful log analysis during investigations.