---
title: "CVE-2026-44327: free5GC's NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler"
url: https://erroneo.us/security/cve/CVE-2026-44327/
description: "CVE-2026-44327 (github.com/free5gc/nef (Go)): free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's NEF mounts the…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-05-27
date_modified: 2026-06-08
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-44327"
kev: false
cvss: 10
epss: 0.0053
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.5% , percentile 44: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 44% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes github.com/free5gc/nef (Go) <= 1.2.3, no fixed version listed . Check your lockfile, including transitive dependencies.

## What it is

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 packages

- Go `github.com/free5gc/nef` <= 1.2.3 → fixed: none listed

## Affected products (CVE record)

- free5gc free5gc: < 4.2.2

## Severity

- GitHub_M CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H`
- GitHub CVSS 3.1: 10.0 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact partial .
- FIRST EPSS (model of 2026-10-21): 0.53% probability of exploitation activity in the next 30 days; percentile 44.

## Sources

- [GitHub Advisory GHSA-cmpj-2x3g-m7g3](https://github.com/advisories/GHSA-cmpj-2x3g-m7g3)
- [CVE.org record CVE-2026-44327](https://www.cve.org/CVERecord?id=CVE-2026-44327)
- [NVD entry CVE-2026-44327](https://nvd.nist.gov/vuln/detail/CVE-2026-44327)
- [github.com](https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3)
- [github.com](https://github.com/free5gc/free5gc/issues/861)
- [github.com](https://github.com/free5gc/nef/pull/23)

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Source page: https://erroneo.us/security/cve/CVE-2026-44327/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt