Horizon Alert
Summary of the vulnerability and why it matters
This advisory concerns a vulnerability in Apache CXF, a widely used framework for developing and consuming web services. The issue allows an attacker with a compromised secret to potentially bypass security measures, undermining the integrity of authentication flows and replay protection. While the specific impact depends on how CXF is deployed, it could affect systems handling sensitive authentication and authorization information.
- Allows forged authentication by bypassing security checks.
- Matters for protecting user sessions and preventing repeated attacks.
- Confirm if Apache CXF is used in sensitive authentication paths.
Attack Path
How an attacker could exploit the issue
An attacker with a validly signed JWT, which can be obtained if a client secret is compromised, can exploit a flaw in Apache CXF's `JwtRequestCodeFilter`. This filter incorrectly copies all claims from the JWT into the authorization parameter map without excluding security-sensitive information. By doing so, an attacker can override parameters crucial for protocols like PKCE and OpenID Connect, potentially undermining security measures and enabling replay attacks.
- Attacker must possess a valid signed JWT.
- Filter copies sensitive claims into authorization map.
- Undermines PKCE and OpenID Connect security.
Live Threat
Current exploitation, exposure, and threat context
When supported by the advisory, a client with a compromised or known `client_secret` could substitute security-sensitive parameters in a signed request JWT. This could undermine the integrity of Proof Key for Code Exchange (PKCE) and OpenID Connect replay protection.
- PKCE integrity and replay protection.
- Client with valid signature submits modified parameters.
- Compromised authentication flows.
Operational Fix
Recommended remediation, mitigation, and detection steps
This vulnerability in Apache CXF's JWT processing impacts authentication flows, potentially affecting teams responsible for identity and access management, API gateways, and application platforms. The first step is to identify all instances of the affected component, assess their exposure and business criticality, and locate the accountable system owner to plan remediation.
- Ownership: Identity and API Gateway teams.
- Verify: Reachability and business criticality.
- Action: Plan vendor coordination and upgrades.
