---
id: CVE-2026-44321
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 SMF mounts the UPI management route group without inbound
  OAuth2 middleware. The POST /upi/v1/upNodesLinks create-or-update handler
  accepts attack…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-306
  - CWE-617
  - 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-2026-44321'
references:
  - url: 'https://github.com/free5gc/free5gc/issues/906'
    label: security-advisories@github.com
  - url: 'https://github.com/free5gc/free5gc/security/advisories/GHSA-44qj-cghf-9p97'
    label: security-advisories@github.com
  - url: >-
      https://github.com/free5gc/smf/commit/e0974e07ddab44a67d36a563cca383b2449e33e5
    label: security-advisories@github.com
  - url: 'https://github.com/free5gc/smf/pull/203'
    label: security-advisories@github.com
  - url: 'https://github.com/free5gc/free5gc/security/advisories/GHSA-44qj-cghf-9p97'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00606
epssPercentile: 0.47745
ingestedAt: '2026-10-14T20:53:12.330Z'
---

## Overview

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's SMF mounts the UPI management route group without inbound OAuth2 middleware. The POST /upi/v1/upNodesLinks create-or-update handler accepts attacker-controlled JSON and passes it directly into UpNodesFromConfiguration(), which calls logger.InitLog.Fatalf(...) on several validation failures. One confirmed path is the UE-IP-pool overlap check: a single unauthenticated POST that adds a new UPF whose pool overlaps an existing UPF terminates the entire SMF process (docker ps shows Exited (1)), not just the goroutine. This vulnerability is fixed in 4.2.2.

## Affected

- `free5gc < 4.2.2`

## Remediation

Upgrade past the affected range:

- `free5gc 4.2.2`