Broken access control in AshPhoenix SubdomainHook via a nil tenant in handle_subdomain

{
  "id": "e6524579f0e75dc52525c0ef462e2374a3bae97fd84365f1c91895f701ab32c5",
  "url": "https://osv.dev/vulnerability/CVE-2026-82724",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Broken access control in AshPhoenix SubdomainHook via a nil tenant in handle_subdomain",
    "summary": "Incorrect Authorization vulnerability in ash-project ash_phoenix invokes the SubdomainHook authorization callback with a nil tenant, so tenant-scoped access checks never see the tenant they are meant to enforce. AshPhoenix.LiveView.SubdomainHook.on_mount/4 attached a handle_params hook to assign the tenant and then immediately called handle_subdomain in the same on_mount. The tenant assign is only written when LiveView later runs handle_params, strictly after on_mount returns, so handle_subdomain read an unset assign and ran as apply(m, f, [socket, nil | a]). A consumer gate that halts when the user does not belong to the tenant instead evaluated nil, either crashing or taking a permissive branch, and it was never re-run once the real subdomain was assigned or on later navigations. The fix runs handle_subdomain inside the handle_params hook with the real tenant on every navigation. This issue affects ash_phoenix: from 2.1.26 before 2.3.25.",
    "evidence": "osv:CVE-2026-82724",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-82724",
      "aliases": [
        "CVE-2026-82724",
        "EEF-CVE-2026-82724",
        "GHSA-39c8-xcwr-gqff"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/ash-project/ash_phoenix",
              "type": "GIT",
              "events": [
                {
                  "introduced": "9a5ea4d377bc263de321d79574872a3dfc4fb541"
                },
                {
                  "fixed": "b396e1aa5c6bdec39255f19cf938b539e6d28b71"
                },
                {
                  "introduced": "02277a84d03fb43bdcbbb63dd97f9f1727509d8f"
                },
                {
                  "fixed": "1e38e7dc8838426cc94656238d9208759c661c03"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "9a5ea4d377bc263de321d79574872a3dfc4fb541"
                      },
                      {
                        "fixed": "b396e1aa5c6bdec39255f19cf938b539e6d28b71"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "2.1.26"
                      },
                      {
                        "fixed": "2.3.25"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "b396e1aa5c6bdec39255f19cf938b539e6d28b71"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.3.24",
            "v2.3.23",
            "v2.3.22",
            "v2.3.21",
            "v2.3.20",
            "v2.3.19",
            "v2.3.18",
            "v2.3.17",
            "v2.3.10",
            "v2.3.16",
            "v2.3.15",
            "v2.3.14",
            "v2.3.13",
            "v2.3.12",
            "v2.3.11",
            "v2.3.9",
            "v2.3.8",
            "v2.3.7",
            "v2.3.6",
            "v2.3.5",
            "v2.3.4",
            "v2.3.3",
            "v2.3.2",
            "v2.3.1",
            "v2.3.0",
            "v2.2.0",
            "v2.1.26"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-82724.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:22.659279392Z",
      "provider": "osv",
      "references": [
        "https://cna.erlef.org/cves/CVE-2026-82724.html",
        "https://github.com",
        "https://osv.dev/vulnerability/EEF-CVE-2026-82724",
        "https://repo.hex.pm",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82724.json",
        "https://github.com/ash-project/ash_phoenix/security/advisories/GHSA-39c8-xcwr-gqff",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-82724",
        "https://github.com/ash-project/ash_phoenix/commit/b396e1aa5c6bdec39255f19cf938b539e6d28b71",
        "https://github.com/ash-project/ash_phoenix"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-863"
        ],
        "cna_assigner": "EEF",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82724.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-82724",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 489169,
  "published_at": "2026-08-31T03:07:57.455+00:00"
}