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AshPhoenix Form.Auto leaks submitted params in an unknown _union_type error message

Type: advisorySources: OSV

Generation of Error Message Containing Sensitive Information vulnerability in ash-project ash_phoenix writes the entire raw submitted param map into an exception message, so secrets submitted alongside a union form field leak into logs, crash reports and the dev error page. When AshPhoenix.Form.Auto builds a union sub-form and the submitted _union_type does not match a configured type, both raise sites built the message with inspect(params, pretty: true), embedding the full untrusted param map, and also inspected the internal union constraints[:types]. Because the message is constructed by the library rather than Phoenix's parameter logger, config :phoenix, :filter_parameters never redacts it. An attacker controls both the trigger and the contents: submitting %{"_union_type" => "nope", "password" => "..."} puts the password verbatim in the raised message. The fix reports only the offending _union_type and the valid type names, dropping the param and constraints dumps. This issue affects ash_phoenix: from 1.2.17 before 2.3.25.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-82727
Confirmed fixed CVEs
Not specified
Updated in this feed
5 Nov 2026, 03:52 UTC · Revision 1

Source evidence

AshPhoenix Form.Auto leaks submitted params in an unknown _union_type error message

core-osv · Original source

Published 31 Aug 2026, 03:03 UTC

Generation of Error Message Containing Sensitive Information vulnerability in ash-project ash_phoenix writes the entire raw submitted param map into an exception message, so secrets submitted alongside a union form field leak into logs, crash reports and the dev error page. When AshPhoenix.Form.Auto builds a union sub-form and the submitted _union_type does not match a configured type, both raise sites built the message with inspect(params, pretty: true), embedding the full untrusted param map, and also inspected the internal union constraints[:types]. Because the message is constructed by the library rather than Phoenix's parameter logger, config :phoenix, :filter_parameters never redacts it. An attacker controls both the trigger and the contents: submitting %{"_union_type" => "nope", "password" => "..."} puts the password verbatim in the raised message. The fix reports only the offending _union_type and the valid type names, dropping the param and constraints dumps. This issue affects ash_phoenix: from 1.2.17 before 2.3.25.

osv:CVE-2026-82727
Complete source record
{
  "id": "8d6cc79894179b09ce74253540860e176c9d7b2afc2843d573e6074827a7a018",
  "url": "https://osv.dev/vulnerability/CVE-2026-82727",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "AshPhoenix Form.Auto leaks submitted params in an unknown _union_type error message",
    "summary": "Generation of Error Message Containing Sensitive Information vulnerability in ash-project ash_phoenix writes the entire raw submitted param map into an exception message, so secrets submitted alongside a union form field leak into logs, crash reports and the dev error page. When AshPhoenix.Form.Auto builds a union sub-form and the submitted _union_type does not match a configured type, both raise sites built the message with inspect(params, pretty: true), embedding the full untrusted param map, and also inspected the internal union constraints[:types]. Because the message is constructed by the library rather than Phoenix's parameter logger, config :phoenix, :filter_parameters never redacts it. An attacker controls both the trigger and the contents: submitting %{\"_union_type\" => \"nope\", \"password\" => \"...\"} puts the password verbatim in the raised message. The fix reports only the offending _union_type and the valid type names, dropping the param and constraints dumps. This issue affects ash_phoenix: from 1.2.17 before 2.3.25.",
    "evidence": "osv:CVE-2026-82727",
    "products": [],
    "severity": "low",
    "structured": {
      "id": "CVE-2026-82727",
      "aliases": [
        "CVE-2026-82727",
        "EEF-CVE-2026-82727",
        "GHSA-5xf4-hgcq-xw7v"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/ash-project/ash_phoenix",
              "type": "GIT",
              "events": [
                {
                  "introduced": "a3436fcc321e3b34c242cceaf62c3c92bc1a452b"
                },
                {
                  "fixed": "0c1775c3cf8988f9abd10a8f92315afc5f06f16d"
                },
                {
                  "introduced": "c7e220099edd5e10f7ad8fef6387169b2551f96f"
                },
                {
                  "fixed": "1e38e7dc8838426cc94656238d9208759c661c03"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "a3436fcc321e3b34c242cceaf62c3c92bc1a452b"
                      },
                      {
                        "fixed": "0c1775c3cf8988f9abd10a8f92315afc5f06f16d"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "introduced": "1.2.17"
                      },
                      {
                        "fixed": "2.3.25"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "0c1775c3cf8988f9abd10a8f92315afc5f06f16d"
                      }
                    ],
                    "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",
            "v2.1.25",
            "v2.1.24",
            "v2.1.23",
            "v2.1.22",
            "v2.1.21",
            "v2.1.20",
            "v2.1.19",
            "v2.1.18",
            "v2.1.17",
            "v2.1.16",
            "v2.1.15",
            "v2.1.14",
            "v2.1.12",
            "v2.1.11",
            "v2.1.10",
            "v2.1.9",
            "v2.1.8",
            "v2.1.7",
            "v2.1.6",
            "v2.1.5",
            "v2.1.4",
            "v2.1.3",
            "v2.1.1",
            "v2.0.3",
            "v2.0.2",
            "v2.0.1",
            "v2.0.0-rc.8",
            "v2.0.0-rc.7",
            "v2.0.0-rc.6",
            "v2.0.0-rc.5",
            "v2.0.0-rc.4",
            "v2.0.0-rc.3",
            "v2.0.0-rc.2",
            "v2.0.0-rc.1",
            "v2.0.0-rc.0",
            "v1.3.4",
            "v1.3.3",
            "v1.3.2",
            "v1.3.1",
            "v1.3.0",
            "v1.2.26",
            "v1.2.25",
            "v1.2.24",
            "v1.2.23",
            "v1.2.22",
            "v1.2.21",
            "v1.2.20",
            "v1.2.19",
            "v1.2.18",
            "v1.2.17"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-82727.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:42.443757901Z",
      "provider": "osv",
      "references": [
        "https://cna.erlef.org/cves/CVE-2026-82727.html",
        "https://github.com",
        "https://osv.dev/vulnerability/EEF-CVE-2026-82727",
        "https://repo.hex.pm",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82727.json",
        "https://github.com/ash-project/ash_phoenix/security/advisories/GHSA-5xf4-hgcq-xw7v",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-82727",
        "https://github.com/ash-project/ash_phoenix/commit/0c1775c3cf8988f9abd10a8f92315afc5f06f16d",
        "https://github.com/ash-project/ash_phoenix"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-209"
        ],
        "cna_assigner": "EEF",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/82xxx/CVE-2026-82727.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-82727",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 510016,
  "published_at": "2026-08-31T03:03:58.982+00:00"
}