In Eclipse Vert.x versions [4.0.0, 4.5.34] or [5.0.0,5.0.12] or [5.1.0,5.1.9] or [5.2.0, 5.2.0], a scope bypass vulnerability exists in Eclipse Vert.x Webs ChainAuthHandler when used with scope-requiring authentication handlers such as JWTAuthHandler or OAuth2AuthHandler. When a user is already authenticated on the routing context by a preceding handler in the request pipeline, ChainAuthHandler skips all scope validation configured via withScope() or withScopes(). This affects both any() and all() chain modes.
The root cause is that postAuthentication() relies on internal state that is only set during the authenticate() phase, which is skipped entirely for pre-authenticated users. In any() mode, the absence of this state causes the method to fall through without delegating scope checks to any handler. In all() mode, scope checks are unconditionally skipped.
This allows a user with a valid token but insufficient scopes to access resources protected by scope requirements, provided they were authenticated by an earlier handler in the pipeline. The most common trigger is overlapping authentication handlers on nested routes, where a parent route authenticates broadly and a child route uses a chain to enforce specific scopes.
The impacted component Maven coordinate is io.vertx:vertx-web
Weakness
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Vert.x | Eclipse | 4.5.0 (including) | 4.5.35 (excluding) |
| Vert.x | Eclipse | 5.0.0 (including) | 5.1.10 (excluding) |
| Vert.x | Eclipse | 5.2.0 (including) | 5.2.0 (including) |
Potential Mitigations
- Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries.
- Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
- For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page.
- One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.