Description
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 OAuth2/bearer-token authorization middleware. A network attacker who can reach SMF on the SBI can hit UPI endpoints with no Authorization header at all, and the requests reach the SMF business handlers. In the running Docker lab this was directly demonstrated for read (GET /upi/v1/upNodesLinks), write (POST /upi/v1/upNodesLinks with attacker-controlled UP-node and link payload), and delete (DELETE /upi/v1/upNodesLinks/{nodeID}) operations. This vulnerability is fixed in 4.2.2.
Affected products
free5gc: free5gc
References6
- github.com/free5gc/free5gc/security/advisories/GHSA-3258-qmv8-f… ExploitVendor Advisory
- github.com/free5gc/free5gc/security/advisories/GHSA-3258-qmv8-f… ExploitVendor Advisory
- github.com/free5gc/smf/commit/e23ce97565f285eb99eed153743c62bf4… Patch
- github.com/free5gc/smf/pull/197 Issue TrackingPatch
- github.com/free5gc/free5gc/issues/887 ExploitIssue Tracking
- github.com/free5gc/free5gc/issues/887 ExploitIssue Tracking
Metrics
- CVSS 3.1
-
10.0
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H - EPSS — exploit probability
- 0% percentile: 27 · as of 14 November 2026
- CWE
- CWE-306CWE-862
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.