---
id: CVE-2026-44327
title: free5GC is an open-source implementation of the 5G core network
summary: >-
  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…
severity: critical
cvss: 10
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H'
cwe:
  - CWE-306
  - CWE-862
vendor: free5gc
product: free5gc
affected:
  - free5gc < 4.2.2
patched:
  - free5gc 4.2.2
published: '2026-05-27'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T20:10:00.190'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-44327'
references:
  - url: 'https://github.com/free5gc/free5gc/issues/861'
    label: security-advisories@github.com
  - url: 'https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3'
    label: security-advisories@github.com
  - url: 'https://github.com/free5gc/nef/pull/23'
    label: security-advisories@github.com
  - url: 'https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-44327'
  - url: 'https://github.com/free5gc/free5gc'
tags:
  - nvd
  - osv
  - go
epss: 0.00311
epssPercentile: 0.2383
aliases:
  - GHSA-cmpj-2x3g-m7g3
  - GO-2026-5326
ecosystem: go
ingestedAt: '2026-07-21T19:04:58.762Z'
---

## Overview

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

- `free5gc < 4.2.2`

## Remediation

Upgrade past the affected range:

- `free5gc 4.2.2`

## Package advisory (CVE-2026-44327)

Affected packages:

- `github.com/free5gc/nef <= 1.2.3`

Source: https://osv.dev/vulnerability/GHSA-cmpj-2x3g-m7g3