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Vulnerability record · CVE-2026-44327 · published 27 May 2026

CVE-2026-44327: Free5gc missing authentication for critical function vulnerability

Free5gc · Free5gc

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.

10.0 CVSS 3.1 Critical EPSS 0.53% · top 57.5% CWE-306 · Missing authentication for critical functionCWE-862 · Missing authorization
10.0CVSS 3.1 base score
0.53%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 3 tagged exploit
17 Jun 2026Last modified by NVD

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/free5gc/free5gc/issues/861 ExploitIssue Tracking
https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3 ExploitVendor Advisory
https://github.com/free5gc/nef/pull/23 Issue TrackingPatch
https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3 ExploitVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-44327), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.