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The vulnerability is a classic case of a hardcoded cryptographic secret, specifically a JSON Web Token (JWT) signing secret. It resides in the API server component of LightRAG, a Retrieval-Augmented Generation (RAG) framework. When the `AUTH_ACCOUNTS` environment variable is set to enable user authentication, the API server requires a `TOKEN_SECRET` to sign and verify JWTs. However, in versions up to and including v1.4.10, if the `TOKEN_SECRET` environment variable is not explicitly set, the system falls back to a hardcoded default value: lightrag-jwt-default-secret. This default secret is publicly known and documented in the project’s own security guide as a placeholder example[reference:0].
An attacker can exploit this vulnerability without any prior authentication. Using the publicly known default secret, they can forge a valid JWT. The steps for exploitation are straightforward:
1. The attacker identifies a LightRAG instance where authentication is enabled (via AUTH_ACCOUNTS) but the `TOKEN_SECRET` is not configured, making the system use the insecure default secret.
2. Using a tool or library like PyJWT, the attacker crafts a JWT. This token includes a payload (claims) such as `{“sub”: “admin”, “role”: “user”}` to impersonate a privileged user.
3. The attacker signs this JWT using the known default secret (lightrag-jwt-default-secret) and the `HS256` algorithm.
4. The attacker sends a request to any protected API endpoint, including the forged token in the `Authorization: Bearer
5. The server’s AuthHandler, which uses the same hardcoded secret for verification, validates the forged token as legitimate, granting the attacker full access to the endpoint and bypassing all authentication checks.
This flaw effectively nullifies any authentication mechanism, allowing an unauthenticated attacker to gain unauthorized access to all protected endpoints. The risk is further heightened because the default secret is included in the project’s documentation, making it exceptionally easy to discover.
DailyCVE Form:
Platform: LightRAG API
Version: ≤1.4.10
Vulnerability: Hardcoded JWT Secret
Severity: Critical (CVSS 9.8)
Date: 2024-12-15
Prediction: Patch available in v1.5.0 (est. 2025-01-15)
Analytics under heading What Undercode Say:
Detection: To check if an instance is vulnerable, an attacker might look for the absence of the `TOKEN_SECRET` environment variable or attempt to forge a token.
Impact: Exploitation can lead to complete account takeover, data breaches, and unauthorized system access.
Tooling: Using tools like `Burp Suite` or custom Python scripts with `PyJWT` to forge tokens is common for this type of vulnerability.
Example: Forging a JWT with the default secret
python3 -c "
import jwt
token = jwt.encode({'sub': 'admin', 'role': 'admin'}, 'lightrag-jwt-default-secret', algorithm='HS256')
print(f'Forged Token: {token}')
"
Use the token in a request
curl -X GET http://target-ip:9621/protected-endpoint -H "Authorization: Bearer <Forged_Token>"
Exploit:
1. Discovery: Identify the target LightRAG API server.
- Token Forging: Use `PyJWT` with the known default secret to craft a token with arbitrary claims.
- Access: Send requests to protected endpoints using the forged token in the `Authorization` header, gaining unauthorized access to the API.
Protection from this CVE:
- Upgrade: Immediately update LightRAG to the latest version where this issue is patched.
- Mitigation: If a patch is not yet available, ensure that the `TOKEN_SECRET` environment variable is explicitly set to a strong, unique secret for all production deployments. The server will refuse to start if authentication is enabled but a custom secret is not provided.
- Hardening: As a defense-in-depth measure, restrict network access to the LightRAG API server to only trusted clients using a firewall or an API gateway.
Impact:
Authentication Bypass: Attackers can bypass all authentication mechanisms without any credentials.
Privilege Escalation: By forging a token with `admin` claims, an attacker can gain full administrative privileges.
Complete System Compromise: Unauthorized access to the API can lead to data theft, data manipulation, and potentially remote code execution, depending on the exposed endpoints.
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Sources:
Reported By: github.com
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