CVE-2022-31186 is an information disclosure vulnerability affecting NextAuth.js, an open-source authentication library widely used in Next.js applications. The vulnerability exists in versions prior to v4.10.2 and v3.29.9 of the next-auth package. Specifically, during OAuth error handling, sensitive information such as identity provider secrets can be logged at a level accessible to users with log access privileges. This occurs because the provider information, which may include confidential OAuth client secrets, is logged at a standard log level rather than being restricted to debug-level logs. An attacker who gains access to these logs can extract these secrets and potentially impersonate the client application to request extensive permissions from the identity provider, leading to further compromise of the authentication flow and user data. The issue was addressed by moving the logging of provider information to the debug log level and by adding warnings against enabling debug mode in production environments. Additionally, the next-auth library introduced a logger configuration option allowing developers to sanitize logs if upgrading is not immediately feasible. This vulnerability falls under CWE-532, which concerns the insertion of sensitive information into log files, a common vector for unintended data exposure. While no known exploits have been reported in the wild, the vulnerability poses a risk in environments where log files are accessible to unauthorized or less trusted users. Exploitation requires access to logs, which may be possible in multi-tenant hosting environments, shared servers, or through compromised accounts with log viewing privileges. The vulnerability does not require user interaction but does require that the application is running a vulnerable version of next-auth and that debug logging is enabled or logs are otherwise accessible.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on NextAuth.js for authentication in web applications handling sensitive or regulated data. Disclosure of identity provider secrets can lead to unauthorized access to user accounts, data breaches, and potential compliance violations under regulations such as GDPR. The ability to impersonate clients and request extensive permissions could result in privilege escalation, data exfiltration, or unauthorized actions on behalf of users. Organizations in sectors such as finance, healthcare, and government, which often use OAuth-based authentication and have stringent data protection requirements, are particularly at risk. Additionally, the exposure of secrets in logs can undermine trust in authentication mechanisms and lead to costly incident response and remediation efforts. Since the vulnerability requires log access, environments with inadequate log access controls or shared infrastructure are more vulnerable. The absence of known exploits suggests that proactive patching and log management can effectively mitigate risk before exploitation occurs.

European organizations should prioritize upgrading next-auth to versions v4.10.2 or later, or v3.29.9 or later, to ensure the vulnerability is patched. If immediate upgrading is not possible, organizations should configure the logger option to sanitize logs and prevent sensitive information from being recorded. It is critical to disable debug logging in production environments to avoid inadvertent exposure of secrets. Access to log files must be strictly controlled using role-based access controls (RBAC) and monitored for unauthorized access attempts. Organizations should audit existing logs for any sensitive information leakage and securely purge or redact such data. Implementing centralized log management solutions with encryption and access controls can further reduce exposure risk. Regular security reviews of authentication configurations and secrets management practices are recommended. Additionally, organizations should educate developers and operations teams about the risks of logging sensitive data and enforce secure coding and deployment standards to prevent similar issues.