CVE-2026-84685 in React Native Auth0
Summary
by MITRE • 09/09/2026
The react-native-auth0 SDK's web platform implementation does not scope its in-memory token cache to individual user sessions when operating in a server-side rendering (SSR) environment where module state persists across HTTP requests. Under the listed preconditions, tokens cached in module memory can be retrieved across subsequent requests processed by the same server runtime.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified within the react-native-auth0 SDK's web platform implementation represents a critical flaw in session management and token storage mechanisms when deployed in server-side rendering environments. This issue stems from an architectural oversight where the library utilizes module-level memory to cache authentication tokens rather than isolating them within specific user sessions or request contexts. In standard client-side applications, this behavior is generally benign because each browser tab or instance maintains its own isolated JavaScript execution context and memory space. However, in server-side rendering scenarios using Node.js or similar runtimes that maintain persistent module state across multiple HTTP requests, the implications are severe. The SDK fails to scope its in-memory token cache to individual user sessions, meaning that any tokens stored during one request remain accessible for subsequent requests handled by the same runtime instance until the process restarts or memory is explicitly cleared.
From a technical perspective, this flaw constitutes an improper isolation of sensitive data within shared state. When a server processes multiple concurrent or sequential HTTP requests using the same module instance, the authentication context from one user's request can inadvertently leak into another user's session. This occurs because JavaScript modules in Node.js are cached and reused across requests to optimize performance. If the react-native-auth0 SDK stores tokens at the module level without binding them to a unique identifier such as a session ID or request-specific context, it creates a shared resource that is not thread-safe nor request-scoped. Consequently, an attacker who can influence the timing of requests may be able to trigger conditions where their own authentication state interferes with legitimate users, or more critically, if server-side logic fails to properly invalidate tokens upon logout or session expiration, stale credentials might persist and potentially be accessed by other processes within the same runtime environment.
The operational impact of this vulnerability is significant, primarily centering on unauthorized access and identity confusion. An attacker could exploit this state leakage to perform actions under the guise of another user if they can manipulate request routing or timing to align with a victim's active session token being present in memory. This leads directly to broken access control scenarios where authentication assumptions are violated due to shared mutable state. Furthermore, it compromises data integrity and confidentiality as sensitive identity tokens intended for one specific interaction become exposed to unrelated interactions within the same server process. In high-traffic environments or those utilizing connection pooling and persistent workers, this risk is amplified because the likelihood of overlapping request processing increases significantly.
This vulnerability aligns with CWE-613, which describes insufficient session expiration, as well as CWE-200, exposure of sensitive information to an unauthorized actor. The lack of proper scoping for in-memory caches violates fundamental principles of secure state management outlined in industry standards such as OWASP Session Management Cheat Sheet, which mandates that sessions must be isolated and not shared across different users or contexts. In terms of the MITRE ATT&CK framework, this flaw facilitates lateral movement within an application's logic layer by allowing identity confusion, potentially leading to privilege escalation if administrative tokens are cached in a manner accessible to lower-privileged processes or requests.
Mitigation strategies must focus on enforcing strict isolation of authentication state per request rather than relying on global module variables. Developers should refactor the token caching mechanism to utilize context objects that are created and destroyed with each HTTP request, ensuring that no sensitive data persists beyond the lifecycle of a single transaction. Alternatively, implementing server-side session stores such as Redis or database-backed sessions can provide robust isolation guarantees independent of memory management quirks in Node.js modules. It is also advisable to audit third-party SDKs for similar patterns where global state is used without proper scoping mechanisms like WeakMaps keyed by request identifiers. Until a patched version addressing this architectural flaw is released, organizations should consider implementing middleware that clears any potentially sensitive module-level variables after each response is sent or restrict the use of server-side rendering with this specific library until remediation occurs.