Medium · published June 12, 2026
An authentication bypass vulnerability exists in the OAuth2 TokenIntrospectionService in Apache CXF. Due to a missing 'throw' keyword in the security context check, the introspection endpoint (/services/oauth2/introspect) can be accessed by any unauthenticated network attacker. However note that this is a safeguard only in the case that someone forgot to enable authentication on the service. Users are recommended to upgrade to version 4.2.2 or 4.1.7 or 3.6.12, which fixes this issue.
| Product | Versions | Fixed in |
|---|---|---|
| apache/cxf | < 4.1.7 | 4.1.7 |
| apache/cxf | ≥ 4.2.0, < 4.2.2 | 4.2.2 |