CVE-2022-29214 is an open redirect vulnerability classified under CWE-601 affecting the NextAuth.js (next-auth) authentication library used in Next.js applications. This vulnerability exists in versions prior to 3.29.3 and between 4.0.0 and 4.3.3, specifically when developers implement an OAuth 1 provider. The flaw allows an attacker to craft malicious URLs that redirect users to untrusted external sites after authentication flows, exploiting the lack of proper validation on redirect URLs. This can facilitate phishing attacks, credential theft, or other social engineering exploits by misleading users into trusting malicious destinations. The issue arises because the library does not sufficiently restrict or validate the redirect URLs passed during the OAuth authentication process. The maintainers have patched this vulnerability in versions 3.29.3 and 4.3.3 and recommend applying a configuration change in the `callbacks` option as a workaround for those unable to upgrade immediately. No known exploits have been reported in the wild, but the vulnerability's presence in a widely used authentication framework means it poses a significant risk if left unmitigated.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on NextAuth.js for user authentication in web applications. An open redirect can be leveraged by attackers to conduct phishing campaigns targeting employees or customers, potentially leading to credential compromise or unauthorized access to sensitive systems. This risk is heightened in sectors with high-value data such as finance, healthcare, and government services prevalent across Europe. Additionally, compromised authentication flows can undermine trust in digital services and lead to reputational damage and regulatory scrutiny under GDPR if personal data is exposed. While the vulnerability does not directly allow code execution or data breach, the indirect effects through social engineering and redirection to malicious sites can facilitate broader attacks. The medium severity rating reflects the moderate ease of exploitation combined with the potential for significant downstream consequences.

European organizations should prioritize upgrading NextAuth.js to versions 3.29.3 or 4.3.3 or later to fully remediate the vulnerability. For environments where immediate upgrading is not feasible, implement the recommended workaround by configuring the `callbacks` option to strictly validate and whitelist redirect URLs, ensuring only trusted domains are allowed. Additionally, organizations should audit their OAuth 1 provider implementations to confirm no unvalidated redirect parameters are accepted. Implementing web application firewalls (WAFs) with rules to detect and block suspicious redirect patterns can provide an additional layer of defense. User education campaigns to raise awareness about phishing risks associated with unexpected redirects should also be conducted. Finally, monitoring authentication logs for unusual redirect activities or spikes in failed login attempts can help detect exploitation attempts early.