LightRAG: Hardcoded JWT Signing Secret Allows Authentication Bypass

Vulnerability

Description

LightRAG v1.4.10 contains a hardcoded JWT signing secret in lightrag/api/config.py at line 397. When the TOKEN_SECRET environment variable is not set, the library defaults to the static string lightrag-jwt-default-secret. The AuthHandler in lightrag/api/auth.py (lines 24-25) uses this secret to sign and verify JSON Web Tokens, making it possible for anyone who knows the secret to create valid tokens [1][2].

Exploitation

An unauthenticated attacker can exploit this by generating a JWT token using the publicly known default secret. For example, using PyJWT: ``python jwt.encode({"sub": "admin", "role": "user"}, "lightrag-jwt-default-secret", algorithm="HS256") ``

The resulting token can be included in the Authorization header of requests to protected endpoints. Since the server uses the same secret for verification, the forged token is accepted as valid, granting access without proper credentials [2].

Impact

Successful exploitation results in authentication bypass, allowing an attacker to access any API endpoint that requires authentication. This could lead to unauthorized data access, modification, or other actions depending on the permissions of the forged token's claims.

Mitigation

No official patch has been released as of the advisory date. The recommended fix is to require the TOKEN_SECRET environment variable to be explicitly set when AUTH_ACCOUNTS is configured, and to refuse server startup if a custom secret is not provided [2]. Users should set a strong, unique secret and never rely on the default value.