CVE-2023-27490 in NextAuth.js
Summary
by MITRE • 03/09/2023
NextAuth.js is an open source authentication solution for Next.js applications. `next-auth` applications using OAuth provider versions before `v4.20.1` have been found to be subject to an authentication vulnerability. A bad actor who can read traffic on the victim's network or who is able to social engineer the victim to click a manipulated login link could intercept and tamper with the authorization URL to **log in as the victim**, bypassing the CSRF protection. This is due to a partial failure during a compromised OAuth session where a session code is erroneously generated. This issue has been addressed in version 4.20.1. Users are advised to upgrade. Users unable to upgrade may using Advanced Initialization, manually check the callback request for state, pkce, and nonce against the provider configuration to prevent this issue. See the linked GHSA for details.
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Analysis
by VulDB Data Team • 04/02/2023
The vulnerability identified as CVE-2023-27490 affects NextAuth.js, a popular open source authentication solution for Next.js applications that implements OAuth authentication flows. This security flaw specifically targets applications utilizing OAuth provider versions prior to v4.20.1, creating a significant risk for unauthorized access and session hijacking. The vulnerability stems from a critical weakness in the OAuth session management process where session codes are incorrectly generated during compromised authentication sessions, fundamentally undermining the security mechanisms designed to protect user authentication flows.
The technical exploitation of this vulnerability occurs through two primary attack vectors that demonstrate the sophistication of the threat. An attacker with network traffic interception capabilities can capture and modify authorization URLs during the OAuth flow, while social engineering tactics can manipulate users into clicking malicious login links that appear legitimate. The flaw allows attackers to bypass crucial CSRF (Cross-Site Request Forgery) protection mechanisms that are essential for preventing unauthorized authentication attempts. This represents a partial failure in the OAuth session handling process where the system incorrectly generates session codes, creating opportunities for session hijacking and unauthorized access to victim accounts.
The operational impact of this vulnerability extends beyond simple unauthorized access, potentially enabling attackers to establish persistent unauthorized sessions within affected applications. When combined with the partial failure during compromised OAuth sessions, the vulnerability creates conditions where attackers can successfully authenticate as legitimate users without proper credentials. This type of vulnerability directly relates to CWE-352, which addresses Cross-Site Request Forgery, and aligns with ATT&CK technique T1566 for social engineering attacks that manipulate users into performing actions that compromise security. The vulnerability essentially allows attackers to bypass authentication mechanisms entirely, making it particularly dangerous for applications handling sensitive user data and access controls.
Organizations using affected NextAuth.js versions should prioritize immediate upgrades to v4.20.1 to resolve the vulnerability, as this represents the official patch addressing the flawed session code generation process. For those unable to upgrade immediately, several mitigation strategies are available through Advanced Initialization techniques that involve manual verification of callback requests against provider configurations. These manual checks should specifically validate state, pkce, and nonce parameters to ensure proper authentication flow integrity. The recommended approach includes implementing additional validation layers that verify the authenticity of OAuth callbacks before accepting authentication responses, effectively creating redundant security checks that compensate for the vulnerable session handling implementation. Security teams should also consider implementing network monitoring to detect suspicious authentication patterns and potential exploitation attempts during the transition period.