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.
Published: 2026-05-27
Score: 10 Critical
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-cmpj-2x3g-m7g3 free5GC's NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler
History

Wed, 27 May 2026 16:30:00 +0000

Type Values Removed Values Added
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.
Title free5GC: NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler
Weaknesses CWE-306
CWE-862
References
Metrics cvssV3_1

{'score': 10, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-27T15:40:41.569Z

Reserved: 2026-05-05T19:00:06.023Z

Link: CVE-2026-44327

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses