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

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Summary

CVECVE-2026-44327
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-27 17:16:38 UTC
Updated2026-05-28 16:24:54 UTC
Descriptionfree5GC 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.

Risk And Classification

Primary CVSS: v3.1 10 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H

EPSS: 0.000400000 probability, percentile 0.124670000 (date 2026-06-01)

Problem Types: CWE-306 | CWE-862 | CWE-306 CWE-306: Missing Authentication for Critical Function | CWE-862 CWE-862: Missing Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H
3.1CNADECLARED10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Free5gc Free5gc All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Free5gc Free5gc affected < 4.2.2 Not specified

References

ReferenceSourceLinkTags
github.com/free5gc/nef/pull/23 [email protected] github.com Issue Tracking, Patch
github.com/free5gc/free5gc/issues/861 [email protected] github.com Exploit, Issue Tracking
github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com Exploit, Vendor Advisory
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
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