CVE-2026-33065free5GC UDM incorrectly returns 500 for empty supi path parameter in DELETE sdm-subscriptions request

Official description

Free5GC is an open-source Linux Foundation project for 5th generation (5G) mobile core networks. In versions prior to 1.4.2, the UDM incorrectly converts a downstream 400 Bad Request (from UDR) into a 500 Internal Server Error when handling DELETE requests with an empty supi path parameter. This leaks internal error handling behavior and makes it difficult for clients to distinguish between client-side errors and server-side failures. When a client sends a DELETE request with an empty supi (e.g., double slashes // in URL path), the UDM forwards the malformed request to UDR, which correctly returns 400. However, UDM propagates this as 500 SYSTEM_FAILURE instead of returning the appropriate 400 error to the client. This violates REST API best practices for DELETE operations. The issue has been patched in version 1.4.2.

Affected packages & fixed versions

Affected products (as reported)

References

• https://github.com/free5gc/free5gc/security/advisories/GHSA-958m-gxmc-mccm x_refsource_CONFIRM
• https://github.com/free5gc/free5gc/issues/783 x_refsource_MISC
• https://github.com/free5gc/udm/pull/79 x_refsource_MISC
• https://github.com/free5gc/udm/commit/88de9fa74a1b3f3522e53b4cfa2d184712ffa4ee x_refsource_MISC