by Kastro
Paper/Archive/CVE-2026-44327

CVE-2026-44327

free5gc free5gc — free5GC: NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler

EPSS 0.3%public exploitCVSS 10.0
critical.is priorityof 100
45
CVSS 10.0 (CNA)10.0 / 10 × 3030.0Not in CISA KEV+300.0EPSS percentile 24.0.240 × 204.8Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
free5gc< 4.2.2–CNA

Scores by source

GitHub_M (CNA)10.0CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H
CISA ADPSSVCExploitation: poc · Automatable: yes · Technical impact: partial

References

exploitgithub.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3refgithub.com/free5gc/free5gc/issues/861refgithub.com/free5gc/nef/pull/23