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free5GC: UE Security Capability bypass on NGAP PathSwitchRequest

Type: advisorySources: OSV

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, the AMF in Free5GC does not verify the UE Security Capabilities received in NGAP PathSwitchRequest messages against its locally stored values, as mandated by 3GPP TS 33.501 §6.7.3.1. A malicious gNB can overwrite the AMF's stored UE security capabilities with arbitrary values, which are then propagated in PathSwitchRequest Acknowledge messages and subsequent Handover Request messages. This leads to persistent handover denial-of-service for affected UEs. This vulnerability is fixed in 4.2.2.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-42081
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 17:59 UTC · Revision 1

Source evidence

free5GC: UE Security Capability bypass on NGAP PathSwitchRequest

core-osv · Original source

Published 27 May 2026, 15:59 UTC

free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, the AMF in Free5GC does not verify the UE Security Capabilities received in NGAP PathSwitchRequest messages against its locally stored values, as mandated by 3GPP TS 33.501 §6.7.3.1. A malicious gNB can overwrite the AMF's stored UE security capabilities with arbitrary values, which are then propagated in PathSwitchRequest Acknowledge messages and subsequent Handover Request messages. This leads to persistent handover denial-of-service for affected UEs. This vulnerability is fixed in 4.2.2.

osv:CVE-2026-42081
Complete source record
{
  "id": "cc35af9c7d7ab2caff1b57410fb19fff6d964e4ba9f16af50906fc65276e4eed",
  "url": "https://osv.dev/vulnerability/CVE-2026-42081",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "free5GC: UE Security Capability bypass on NGAP PathSwitchRequest",
    "summary": "free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, the AMF in Free5GC does not verify the UE Security Capabilities received in NGAP PathSwitchRequest messages against its locally stored values, as mandated by 3GPP TS 33.501 §6.7.3.1. A malicious gNB can overwrite the AMF's stored UE security capabilities with arbitrary values, which are then propagated in PathSwitchRequest Acknowledge messages and subsequent Handover Request messages. This leads to persistent handover denial-of-service for affected UEs. This vulnerability is fixed in 4.2.2.",
    "evidence": "osv:CVE-2026-42081",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-42081",
      "aliases": [
        "CVE-2026-42081",
        "GHSA-77x9-rf64-92gv",
        "GO-2026-5209"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/free5gc/free5gc",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "8b0f4445fc931638fb624463ce3572a203517679"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.2.2"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:free5gc:free5gc:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.2.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v4.2.1",
            "v4.2.0",
            "v4.1.0",
            "v4.0.1",
            "v4.0.0",
            "v3.4.5",
            "v3.4.4",
            "v3.4.3",
            "v3.4.2",
            "v3.4.1",
            "v3.4.0",
            "v3.3.0",
            "v3.2.1",
            "v3.2.0",
            "v3.1.1",
            "v3.1.0",
            "v3.0.7",
            "v3.0.6",
            "v3.0.5"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42081.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:31.014840715Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42081.json",
        "https://github.com/free5gc/free5gc/security/advisories/GHSA-77x9-rf64-92gv",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-42081"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-358"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42081.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-42081",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 498110,
  "published_at": "2026-05-27T15:59:58.216+00:00"
}