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GHSA-cmpj-2x3g-m7g3
No affected components available
Summary
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. Same root cause as the NEF traffic-influence and PFD-management findings.
Details
Validated against the NEF container in the official Docker compose lab.
- Source repo tag:
v4.2.1 - Running Docker image:
free5gc/nef:v4.2.0 - Runtime NEF commit:
5ce35eab - Docker validation date: 2026-03-11
NEF advertises OAuth2 setting receive from NRF: true, yet the OAM route group is mounted without any inbound auth middleware and answers unauthenticated GETs with 200 OK.
Code evidence (paths in free5gc/nef):
- OAM route group mounted without auth middleware:
NFs/nef/internal/sbi/server.go:60 - OAM route exposed at
/:NFs/nef/internal/sbi/api_oam.go:9 - OAM processor returns
200 OKdirectly:NFs/nef/internal/sbi/processor/oam.go:9 - NEF context only exposes outbound token acquisition (
GetTokenCtx); there is no inbound authorization path:NFs/nef/internal/context/nef_context.go:153
PoC
Reproduced against the running NEF at http://10.100.200.19:8000 with no Authorization header:
curl -i http://10.100.200.19:8000/nnef-oam/v1/
Observed output:
HTTP/1.1 200 OK
null
NEF container logs (docker logs nef) show the request being served while OAuth is enabled:
[INFO][NEF][GIN] | 200 | GET | /nnef-oam/v1/
Impact
Missing inbound authentication (CWE-306) and authorization (CWE-862) on the NEF OAM SBI route group. Severity is scored against the OAM route group's intended capability surface (Operations / Administration / Maintenance), NOT against the current stub handler. The current handler is a stub that returns null, but the defect is route-group-scoped: there is no auth middleware on the group at all, so every future OAM operation added behind this group inherits the missing inbound auth boundary by default.
Any party that can reach NEF on the SBI can:
- Probe and enumerate the OAM route surface anonymously today.
- Hit any future OAM-group endpoint (read, modify, restart-style operations) anonymously, because the auth boundary does not exist for this group.
Operators who assume OAuth2 setting receive from NRF: true enforces inbound auth on NEF are wrong for this route group.
Affected: free5gc v4.2.1.
Upstream issue: https://github.com/free5gc/free5gc/issues/861 Upstream fix: https://github.com/free5gc/nef/pull/23
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.
Active exploitation in the wild has been confirmed. Immediate patching or mitigation is required.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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