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The vulnerability, CVE-2024-56789, stems from a logic flaw within the Auth0-PHP SDK’s token verification routine. When a Symfony application configured with the affected SDK receives a JSON Web Token (JWT), it must validate the `aud` (audience) claim to ensure the token was issued for this specific application. The flawed validation incorrectly accepts an ID token in contexts requiring an access token. While both token types are JWTs, their intended `aud` claims differ fundamentally: an ID token’s audience is the client application itself, whereas an access token’s audience is typically an API identifier. By failing to enforce this distinction, the SDK’s verification routine does not reject an ID token presented to access a protected API endpoint. This allows a malicious actor who possesses a valid ID token (obtained, for example, through a standard login flow) to potentially bypass authorization checks meant to be governed by access tokens, leading to unauthorized access to resources or actions.
Platform: Auth0 Symfony SDK
Version: < 5.6.0
Vulnerability: Improper Audience Validation
Severity: Moderate
Date: 2024-12-17
Prediction: Patched 2024-12-17
What Undercode Say:
composer show auth0/symfony composer update auth0/symfony
// Vulnerable validation logic snippet
if (!$jwt->validates()) {
// Flawed acceptance of ID token 'aud'
}
// Fixed validation in 5.6.0
if (!$jwt->validates('api_audience_string')) {
// Correctly checks for specific access token audience
}
How Exploit:
Attacker acquires own ID token.
Submits token to API endpoint.
SDK incorrectly validates token audience.
Authorization bypass achieved.
Protection from this CVE:
Upgrade to v5.6.0.
Enforce strict token type validation.
Configure correct API audiences.
Impact:
Authentication Bypass Potential.
Privilege Escalation Risk.
Data Confidentiality Compromise.
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Sources:
Reported By: github.com
Extra Source Hub:
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