CVE-2023-46750 is a security vulnerability classified as CWE-601, an 'Open Redirect' issue found in the Apache Software Foundation's Apache Shiro framework. This vulnerability arises specifically when the 'form' authentication mechanism is used. Apache Shiro is a widely used Java security framework that provides authentication, authorization, cryptography, and session management. The open redirect vulnerability allows an attacker to craft a malicious URL that appears to be a legitimate link within an application using Apache Shiro but redirects users to an untrusted external site. This can facilitate phishing attacks, credential theft, or delivery of malware by exploiting user trust in the original domain. The vulnerability affects Apache Shiro versions from the initial release up to 2.0.0-alpha-1. The issue does not require any privileges (PR:N) but does require user interaction (UI:R) to trigger the redirect. The attack vector is network-based (AV:N), meaning it can be exploited remotely without physical access. The vulnerability impacts confidentiality to a limited extent by potentially exposing users to malicious sites but does not affect integrity or availability of the system. The scope is changed (S:C), indicating the vulnerability can affect components beyond the vulnerable module, such as the user's browser session. The Apache Shiro project has addressed this issue in versions 1.13.0 and 2.0.0-alpha-4 and later, recommending users upgrade to these versions to mitigate the risk. No known exploits are currently reported in the wild, but the medium severity score (CVSS 4.7) suggests it should be addressed promptly to prevent exploitation. Given the nature of open redirects, the vulnerability is often leveraged as part of social engineering or phishing campaigns rather than direct system compromise.

For European organizations, the impact of this vulnerability primarily lies in the increased risk of phishing and social engineering attacks targeting employees or customers. Organizations using Apache Shiro for web application security may inadvertently redirect users to malicious sites, undermining user trust and potentially leading to credential compromise or malware infections. This can result in reputational damage, regulatory scrutiny under GDPR if personal data is compromised, and financial losses from fraud or remediation efforts. Since Apache Shiro is used in various enterprise applications, including internal portals and customer-facing services, the risk extends across multiple sectors such as finance, healthcare, government, and e-commerce. The vulnerability does not directly compromise system integrity or availability, but the indirect consequences of successful phishing attacks can be severe. European organizations with strict compliance requirements must also consider the legal implications of failing to protect users from such redirect-based attacks.

To mitigate this vulnerability, European organizations should prioritize upgrading Apache Shiro to version 1.13.0 or later, or 2.0.0-alpha-4 or later, as recommended by the vendor. Beyond patching, organizations should audit their web applications to identify any usage of 'form' authentication in Apache Shiro and verify that redirect URLs are properly validated and sanitized to prevent open redirects. Implementing strict allowlists for redirect destinations and employing Content Security Policy (CSP) headers can reduce the risk of malicious redirections. User education campaigns to raise awareness about phishing risks associated with suspicious URLs can further reduce the likelihood of successful exploitation. Additionally, monitoring web traffic for unusual redirect patterns and integrating web application firewalls (WAFs) with rules to detect and block open redirect attempts can provide an additional security layer. Organizations should also review incident response plans to address potential phishing incidents stemming from this vulnerability.