CVE-2023-41080 is a security vulnerability classified as CWE-601 (Open Redirect) found in the FORM authentication mechanism of Apache Tomcat, a widely used Java-based web server and servlet container. This vulnerability affects Apache Tomcat versions from 8.5.0 through 8.5.92, 9.0.0-M1 through 9.0.79, 10.1.0-M1 through 10.0.12, and 11.0.0-M1 through 11.0.0-M10. The issue is confined to the ROOT (default) web application, where the FORM authentication feature improperly handles redirect URLs after login. An attacker can craft a URL that causes the server to redirect users to an arbitrary, untrusted external site. This can be exploited to facilitate phishing attacks by luring users to malicious websites that appear to be legitimate due to the initial trusted domain. The vulnerability does not require authentication or user interaction beyond clicking a malicious link, making it relatively straightforward to exploit. No public exploit code or active exploitation has been reported to date. The lack of a CVSS score indicates that the vulnerability's impact is recognized but not fully quantified yet. The vulnerability primarily threatens user trust and confidentiality by enabling redirection to potentially harmful sites, but it does not directly compromise server integrity or availability. Older, end-of-life versions of Apache Tomcat may also be affected, increasing the risk for organizations that have not maintained up-to-date software. Since Apache Tomcat is widely deployed in enterprise environments, especially for hosting Java web applications, this vulnerability could have broad implications if not addressed.

For European organizations, the impact of CVE-2023-41080 centers on the risk of phishing and social engineering attacks leveraging trusted domains to redirect users to malicious sites. This can lead to credential theft, malware infection, or unauthorized data disclosure if users are deceived into entering sensitive information on attacker-controlled sites. The vulnerability undermines user trust in web applications hosted on affected Apache Tomcat servers. While it does not directly compromise server confidentiality, integrity, or availability, the indirect consequences can be significant, especially for sectors handling sensitive personal or financial data such as banking, healthcare, and government services. Organizations relying on the ROOT web application or custom applications built on affected Tomcat versions are particularly vulnerable. The absence of known exploits reduces immediate risk but does not eliminate the threat, as attackers may develop exploits in the future. The vulnerability also poses reputational risks if exploited, potentially leading to regulatory scrutiny under GDPR for failure to protect user data and prevent phishing attacks. European organizations with large user bases or public-facing web services should prioritize mitigation to prevent exploitation.

1. Upgrade Apache Tomcat to the latest patched version as soon as it becomes available to ensure the vulnerability is fully addressed. 2. Until patches are applied, implement strict validation and sanitization of redirect URLs within the FORM authentication flow to ensure only trusted internal URLs are accepted. 3. Employ web application firewalls (WAFs) with rules designed to detect and block suspicious redirect patterns targeting the ROOT web application. 4. Educate users and administrators about the risks of phishing attacks leveraging open redirects and encourage vigilance when clicking on links, especially those received via email or untrusted sources. 5. Review and audit all web applications hosted on Apache Tomcat servers to identify any custom redirect logic that could be exploited similarly. 6. Monitor web server logs for unusual redirect requests or patterns indicative of exploitation attempts. 7. Consider implementing Content Security Policy (CSP) headers and other browser-based protections to reduce the impact of malicious redirects. 8. For organizations using older, unsupported Tomcat versions, plan and execute an upgrade strategy to supported releases to reduce exposure to this and other vulnerabilities.