Vulnerability-Lookup

CVE-2026-44327 (GCVE-0-2026-44327)

Vulnerability from cvelistv5 – Published: 2026-05-27 15:40 – Updated: 2026-05-28 14:40

Title

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

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 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.

Severity

10 (Critical)


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

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-05-28 14:38 UTC

CWE

CWE-306 - Missing Authentication for Critical Function
CWE-862 - Missing Authorization

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7761 records in the last 180 days details

References

3 references

URL	Tags
https://github.com/free5gc/free5gc/security/advis…	x_refsource_CONFIRM
https://github.com/free5gc/free5gc/issues/861	x_refsource_MISC
https://github.com/free5gc/nef/pull/23	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
free5gc	free5gc	Affected: < 4.2.2	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-44327

Vulnerability from fkie_nvd - Published: 2026-05-27 17:16 - Updated: 2026-10-14 20:10

Severity

10.0 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H

Summary

References

URL	Tags
security-advisories@github.com	https://github.com/free5gc/free5gc/issues/861	Exploit, Issue Tracking
security-advisories@github.com	https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3	Exploit, Vendor Advisory
security-advisories@github.com	https://github.com/free5gc/nef/pull/23	Issue Tracking, Patch
134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3	Exploit, Vendor Advisory

Impacted products

	Vendor	Product	Version
	free5gc	free5gc	*

JSON

To clipboard

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      "url": "https://github.com/free5gc/nef/pull/23"
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    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Vendor Advisory"
      ],
      "url": "https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-306"
        },
        {
          "lang": "en",
          "value": "CWE-862"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-CMPJ-2X3G-M7G3

Vulnerability from github – Published: 2026-05-08 22:59 – Updated: 2026-07-21 13:57

Summary

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

Details

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 free5gc/nef): - OAM route group mounted without auth middleware: NFs/nef/internal/sbi/server.go:60 - OAM route exposed at /: NFs/nef/internal/sbi/api_oam.go:9 - OAM processor returns 200 OK directly: NFs/nef/internal/sbi/processor/oam.go:9 - NEF context only exposes outbound token acquisition (GetTokenCtx); there is no inbound authorization path: NFs/nef/internal/context/nef_context.go:153

PoC

Reproduced against the running NEF at http://10.100.200.19:8000 with no Authorization header:

curl -i http://10.100.200.19:8000/nnef-oam/v1/

Observed output:

HTTP/1.1 200 OK
null

NEF container logs (docker logs nef) show the request being served while OAuth is enabled:

[INFO][NEF][GIN] | 200 | GET | /nnef-oam/v1/

Impact

Missing inbound authentication (CWE-306) and authorization (CWE-862) on the NEF OAM SBI route group. Severity is scored against the OAM route group's intended capability surface (Operations / Administration / Maintenance), NOT against the current stub handler. The current handler is a stub that returns null, but the defect is route-group-scoped: there is no auth middleware on the group at all, so every future OAM operation added behind this group inherits the missing inbound auth boundary by default.

Any party that can reach NEF on the SBI can: - Probe and enumerate the OAM route surface anonymously today. - Hit any future OAM-group endpoint (read, modify, restart-style operations) anonymously, because the auth boundary does not exist for this group.

Operators who assume OAuth2 setting receive from NRF: true enforces inbound auth on NEF are wrong for this route group.

Affected: free5gc v4.2.1.

Upstream issue: https://github.com/free5gc/free5gc/issues/861 Upstream fix: https://github.com/free5gc/nef/pull/23

Severity

10.0 (Critical)


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

Show details on source website

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/free5gc/nef"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "1.2.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44327"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-306",
      "CWE-862"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-08T22:59:22Z",
    "nvd_published_at": "2026-05-27T17:16:38Z",
    "severity": "CRITICAL"
  },
  "details": "### Summary\nfree5GC\u0027s 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.\n\n### Details\nValidated against the NEF container in the official Docker compose lab.\n- Source repo tag: `v4.2.1`\n- Running Docker image: `free5gc/nef:v4.2.0`\n- Runtime NEF commit: `5ce35eab`\n- Docker validation date: 2026-03-11\n\nNEF advertises `OAuth2 setting receive from NRF: true`, yet the OAM route group is mounted without any inbound auth middleware and answers unauthenticated `GET`s with `200 OK`.\n\nCode evidence (paths in `free5gc/nef`):\n- OAM route group mounted without auth middleware: `NFs/nef/internal/sbi/server.go:60`\n- OAM route exposed at `/`: `NFs/nef/internal/sbi/api_oam.go:9`\n- OAM processor returns `200 OK` directly: `NFs/nef/internal/sbi/processor/oam.go:9`\n- NEF context only exposes outbound token acquisition (`GetTokenCtx`); there is no inbound authorization path: `NFs/nef/internal/context/nef_context.go:153`\n\n### PoC\nReproduced against the running NEF at `http://10.100.200.19:8000` with no `Authorization` header:\n\n```\ncurl -i http://10.100.200.19:8000/nnef-oam/v1/\n```\n\nObserved output:\n```\nHTTP/1.1 200 OK\nnull\n```\n\nNEF container logs (`docker logs nef`) show the request being served while OAuth is enabled:\n```\n[INFO][NEF][GIN] | 200 | GET | /nnef-oam/v1/\n```\n\n### Impact\nMissing inbound authentication (CWE-306) and authorization (CWE-862) on the NEF OAM SBI route group. Severity is scored against the OAM route group\u0027s intended capability surface (Operations / Administration / Maintenance), NOT against the current stub handler. The current handler is a stub that returns `null`, but the defect is route-group-scoped: there is no auth middleware on the group at all, so every future OAM operation added behind this group inherits the missing inbound auth boundary by default.\n\nAny party that can reach NEF on the SBI can:\n- Probe and enumerate the OAM route surface anonymously today.\n- Hit any future OAM-group endpoint (read, modify, restart-style operations) anonymously, because the auth boundary does not exist for this group.\n\nOperators who assume `OAuth2 setting receive from NRF: true` enforces inbound auth on NEF are wrong for this route group.\n\nAffected: free5gc v4.2.1.\n\nUpstream issue: https://github.com/free5gc/free5gc/issues/861\nUpstream fix: https://github.com/free5gc/nef/pull/23",
  "id": "GHSA-cmpj-2x3g-m7g3",
  "modified": "2026-07-21T13:57:54Z",
  "published": "2026-05-08T22:59:22Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/free5gc/free5gc/security/advisories/GHSA-cmpj-2x3g-m7g3"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44327"
    },
    {
      "type": "WEB",
      "url": "https://github.com/free5gc/free5gc/issues/861"
    },
    {
      "type": "WEB",
      "url": "https://github.com/free5gc/nef/pull/23"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/free5gc/free5gc"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "free5GC\u0027s NEF nnef-oam route group is unauthenticated; no-token requests reach the OAM handler"
}

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CVE-2026-44327 (GCVE-0-2026-44327)

FKIE_CVE-2026-44327

GHSA-CMPJ-2X3G-M7G3

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