CVE-2026-42459: Free5GC UDM has Improper Input Validation and Generation of Error Messages Containing Sensitive Information

The free5GC UDM component fails to validate the supi path parameter in six GET handlers of the nudm-sdm (Subscriber Data Management) service. An unauthenticated attacker can inject control characters into the SUPI parameter, causing UDM to forward a malformed request to UDR and return a 500 Internal Server Error response that exposes internal infrastructure details.