free5GC's NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-44327: 0.31% estimated exploitation activity in the next 30 days; percentile 24.05 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary 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. Same root cause as the NEF traffic-influence and PFD-management findings. Details Validated against the NEF container in the official Docker compose lab. - Source repo tag: v4.2.1 - Running Docker image: free5gc/nef:v4.2.0 - Runtime NEF commit: 5ce35eab - Docker validation date: 2026-03-11 NEF advertises OAuth2 setting receive from NRF: true, yet the OAM route group is mounted without any inbound auth middleware and answers unauthenticated GETs with 200 OK. Code evidence (paths in…

Published by the source

8 May 2026, 22:59 UTC

Last modified by the source

8 Jun 2026, 23:48 UTC

Source last checked

26 Oct 2026, 15:23 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-cmpj-2x3g-m7g3

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# Patch Next advisory brief: CVE-2026-44327

Advisory: free5GC's NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler
IDs: CVE-2026-44327, GHSA-cmpj-2x3g-m7g3
Record: https://patchnext.com/advisories/cve-2026-44327 (revision 1, source checked 26 Oct 2026, 15:23 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 10.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/free5gc/nef: affected <= 1.2.3

## Suggested inspection (read-only)
- Go github.com/free5gc/nef: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/free5gc/nef.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-cmpj-2x3g-m7g3 (GitHub-reviewed advisory GHSA-cmpj-2x3g-m7g3 lists affected ranges: Go github.com/free5gc/nef >=0 <=1.2.3)

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