CVE-2026-33065 free5GC UDM incorrectly returns 500 for empty supi path parameter in DELETE sdm-subscriptions request
An attacker can trigger internal error handling leaks by sending malformed requests, revealing server-side failure details instead of standard client errors.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33065?
CVE-2026-33065 is a medium-severity vulnerability in free5gc, published on 20 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-209
Which versions are affected by CVE-2026-33065?
3 open source packages ship an affected version, including github.com/free5gc/udm. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/free5gc/udm Go | All versions | 1.4.2 |
github.com/free5gc/udm Go | All versions | 1.4.2 |
github.com/free5gc/udm Go | All versions | 1.4.2 |
Products include Free5gc Udm.
How do I fix CVE-2026-33065?
Upgrade github.com/free5gc/udm to 1.4.2 or later.
Is CVE-2026-33065 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33065 exists.
Other vulnerabilities in free5gc
- CVE-2026-33064 free5GC UDM DataChangeNotification Procedure Panic Due to Nil Pointer Dereference
- CVE-2026-33191 free5GC UDM vulnerable to null byte injection in URL path parameters causing 500 Internal Server Error
- CVE-2026-33192 free5GC UDM incorrectly returns 500 for empty supi path parameter in PATCH sdm-subscriptions reques
- CVE-2023-46324 free5GC udm vulnerable to Invalid Curve Attack
- CVE-2026-27642 free5GC has Improper Input Validation in UDM UEAU Service
Sources
Also known as GHSA-958m-gxmc-mccm, GO-2026-4758, ROOT-OS-UBUNTU-2204-CVE-2026-33065.