CVE-2026-44327
CriticalSummary
In versions prior to 4.2.2, free5GC's NEF did not require OAuth2/bearer-token authorization for the nnef-oam route group. A network attacker could access the OAM route without an authorization header, resulting in a 200 OK response.
Risk Assessment
The lack of authorization for OAM operations poses a risk of unauthorized access to network management functions, potentially leading to serious security breaches.
Recommendation
It is recommended to upgrade to version 4.2.2 or later to implement proper authorization mechanisms for the OAM route group.
Original NVD description (English source)
free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's NEF mounts the nnef-oam route group without inbound OAuth2/bearer-token authorization. A network attacker who can reach NEF on the SBI can hit the OAM route with no Authorization header at all and the handler returns 200 OK. The current OAM handler is a stub that returns null, but the structural defect is route-group-scoped: the entire OAM route group has no inbound auth middleware, so every future OAM operation added to this group inherits the missing auth boundary by default. This vulnerability is fixed in 4.2.2.