{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "2.1.26"
              },
              {
                "fixed": "2.3.25"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "02277a84d03fb43bdcbbb63dd97f9f1727509d8f"
            },
            {
              "fixed": "1e38e7dc8838426cc94656238d9208759c661c03"
            },
            {
              "fixed": "8306f29e77526840c89f3cd244996ce7c0fa2cda"
            }
          ],
          "repo": "https://github.com/ash-project/ash_phoenix",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-rpf8-q9jh-qxrr"
  ],
  "database_specific": {
    "cna_assigner": "EEF",
    "cwe_ids": [
      "CWE-178",
      "CWE-625"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82726.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "introduced": "9a5ea4d377bc263de321d79574872a3dfc4fb541"
          },
          {
            "fixed": "8306f29e77526840c89f3cd244996ce7c0fa2cda"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "Permissive Regular Expression vulnerability in ash-project ash_phoenix lets a remote client select the tenant an Ash application uses, or degrade the request, by sending a crafted Host header.\n\nAshPhoenix.Helpers.get_subdomain/2 stripped the root domain with String.replace(host, ~r/.?#{root_host}/, \"\"). The root host was interpolated raw, so each . became a wildcard and any metacharacter a pattern, and the replace was global and unanchored, so a match was removed from anywhere in the string. With root_host example.com, Host: foo.exampleXcom.attacker.net returned the tenant foo.attacker.net. A metacharacter-bearing or nil root host degraded the pattern or raised on every request. The comparison was also case-sensitive, so TENANT.EXAMPLE.COM and EXAMPLE.COM slipped past the root-host allowlist. conn.host comes from the client Host header. The fix matches the root host case-insensitively and only as an exact trailing suffix.\n\nThis issue affects ash_phoenix: from 2.1.26 before 2.3.25.",
  "id": "CVE-2026-82726",
  "modified": "2026-09-03T03:30:18.850156752Z",
  "published": "2026-08-31T03:05:38.612Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-82726.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-82726"
    },
    {
      "type": "WEB",
      "url": "https://repo.hex.pm"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82726.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/ash-project/ash_phoenix/security/advisories/GHSA-rpf8-q9jh-qxrr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-82726"
    },
    {
      "type": "FIX",
      "url": "https://github.com/ash-project/ash_phoenix/commit/8306f29e77526840c89f3cd244996ce7c0fa2cda"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ash-project/ash_phoenix"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "AshPhoenix get_subdomain maps a crafted or differently-cased Host header to an arbitrary tenant"
}