What’s Vulnerable › Vulnerabilities

CVE-2026-44327: free5GC: NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler

• Severity: critical (CVSS 10.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-05-27 · updated 2026-10-14
• Weakness: CWE-306

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.

Affected products

• free5gc: before 4.2.2 — fixed in 4.2.2

How to fix

Upgrade to a fixed version: free5gc 4.2.2. Check the vendor advisory for mitigations.

References

• https://github.com/free5gc/free5gc/issues/861
• https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3
• https://github.com/free5gc/nef/pull/23
• https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3

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