CVE-2023-46749 is a path traversal vulnerability identified in the Apache Shiro framework, versions prior to 1.13.0 and 2.0.0-alpha-4. Apache Shiro is a widely used Java security framework that provides authentication, authorization, cryptography, and session management. The vulnerability arises due to improper limitation of pathname to a restricted directory (CWE-22), which allows an attacker to manipulate file paths when path rewriting is used in conjunction with the framework. This flaw can be exploited to bypass authentication mechanisms by crafting malicious requests that traverse directories and access unauthorized resources. The vulnerability does not directly impact confidentiality but has a high impact on integrity, as it allows unauthorized users to bypass authentication controls, potentially gaining elevated privileges or unauthorized access to protected resources. The CVSS v3.1 base score is 6.5 (medium severity), with an attack vector of network (AV:N), low attack complexity (AC:L), requiring low privileges (PR:L), no user interaction (UI:N), and unchanged scope (S:U). No known exploits are currently reported in the wild. Mitigation involves upgrading Apache Shiro to version 1.13.0 or later, or 2.0.0-alpha-4 or later. Alternatively, enabling the 'blockSemicolon' configuration option, which is enabled by default in patched versions, prevents exploitation by blocking semicolon characters in paths that facilitate traversal attacks.

For European organizations, this vulnerability poses a significant risk especially to those relying on Apache Shiro for securing web applications and services. An authentication bypass can lead to unauthorized access to sensitive systems, data manipulation, and potential lateral movement within networks. This can compromise business-critical applications, customer data, and intellectual property. Sectors such as finance, healthcare, government, and critical infrastructure, which often use Java-based enterprise applications, could face increased risk of fraud, data breaches, and service disruption. The medium severity score indicates a moderate but tangible threat that could be leveraged by attackers with network access and some level of privileges. Given the widespread use of Apache Shiro in Europe, the vulnerability could be exploited in targeted attacks or automated scanning campaigns if unpatched systems remain exposed.

European organizations should prioritize upgrading Apache Shiro to version 1.13.0 or 2.0.0-alpha-4 and above as the primary mitigation step. If immediate upgrade is not feasible, ensure that the 'blockSemicolon' configuration option is enabled to prevent path traversal via semicolon injection. Additionally, organizations should audit their web applications to identify usage of vulnerable Shiro versions, especially in environments where path rewriting is implemented. Implement strict input validation and sanitization on all user-supplied path parameters to reduce the risk of traversal attacks. Employ Web Application Firewalls (WAFs) with rules designed to detect and block path traversal attempts. Regularly monitor logs for unusual authentication bypass attempts or suspicious path access patterns. Finally, integrate vulnerability scanning and patch management processes to detect and remediate vulnerable Shiro instances promptly.