CVE-2026-44321: FREE5GC

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's SMF mounts the UPI management route group without inbound OAuth2 middleware. The POST /upi/v1/upNodesLinks create-or-update handler accepts attacker-controlled JSON and passes it directly into UpNodesFromConfiguration(), which calls logger.InitLog.Fatalf(...) on several validation failures. One confirmed path is the UE-IP-pool overlap check: a single unauthenticated POST that adds a new UPF whose pool overlaps an existing UPF terminates the entire SMF process (docker ps shows Exited (1)), not just the goroutine. This vulnerability is fixed in 4.2.2.

Affected products

• FREE5GC FREE5GC: before 4.2.2 (fixed in 4.2.2)

Published 2026-05-27. Last modified 2026-06-17.