CVE-2026-44327

Critical

Description

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.

SeverityCritical

CVSS10.0

Exploit probability—

ProductFree5gc

PublishedMay 27, 2026

First seenMay 27, 2026

Weakness typeCWE-306Missing authentication for critical function CWE-862Missing authorization

How to fix

Update

free5gc free5gc4.2.2 or later

Affected products

Product	Affected versions	Fixed in
free5gc free5gc	v < 4.2.2	4.2.2
github.com/free5gc/nefGo	v ≤ 1.2.3, No range specified	—

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.