AshPostgres returns another tenant's record for a skipped upsert when return_skipped_upsert? is set

{
  "id": "9ed328c674ab206e6a0de7da30ea00561dc44d6209ab58b391138a7c80d29a08",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-115635",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "AshPostgres returns another tenant's record for a skipped upsert when return_skipped_upsert? is set",
    "summary": "Incorrect Authorization vulnerability in ash-project ash_postgres allows a user to read another tenant's record through a skipped upsert. When Ash.bulk_create/4 or a single create runs as an upsert with return_skipped_upsert?: true and the upsert is skipped (for example because its upsert_condition does not hold), AshPostgres.DataLayer reads the existing row back by the upsert identity in do_bulk_create/3 and upsert/4. That lookup did not apply the resource's attribute multitenancy, so on a resource using strategy :attribute it could match and return the row of another tenant with the same identity values, exposing its fields to the caller. This issue affects ash_postgres: from 2.6.22 before 2.15.2.",
    "evidence": "cve:CVE-2026-115635",
    "products": [
      {
        "name": {
          "value": "ash_postgres",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "ash_postgres",
          "evidence": "/containers/cna/affected/1/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-115635",
      "aliases": [
        "CVE-2026-115635"
      ],
      "metrics": [
        {
          "format": "CVSS",
          "cvssV4_0": {
            "Safety": "NOT_DEFINED",
            "version": "4.0",
            "Recovery": "NOT_DEFINED",
            "baseScore": 6,
            "Automatable": "NOT_DEFINED",
            "attackVector": "NETWORK",
            "baseSeverity": "MEDIUM",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
            "providerUrgency": "NOT_DEFINED",
            "userInteraction": "NONE",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "privilegesRequired": "LOW",
            "subIntegrityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "subAvailabilityImpact": "NONE",
            "vulnAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "affected": [
        {
          "cpes": [
            "cpe:2.3:a:ash-project:ash_postgres:*:*:*:*:*:*:*:*"
          ],
          "repo": "https://github.com/ash-project/ash_postgres",
          "vendor": "ash-project",
          "modules": [
            "'Elixir.AshPostgres.DataLayer'"
          ],
          "product": "ash_postgres",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.22",
              "lessThan": "2.15.2",
              "versionType": "semver"
            }
          ],
          "packageURL": "pkg:hex/ash_postgres",
          "packageName": "ash_postgres",
          "programFiles": [
            "lib/data_layer.ex"
          ],
          "collectionURL": "https://repo.hex.pm",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "'Elixir.AshPostgres.DataLayer':do_bulk_create/3"
            },
            {
              "name": "'Elixir.AshPostgres.DataLayer':upsert/4"
            },
            {
              "name": "'Elixir.AshPostgres.DataLayer':bulk_create/3"
            }
          ]
        },
        {
          "cpes": [
            "cpe:2.3:a:ash-project:ash_postgres:*:*:*:*:*:*:*:*"
          ],
          "repo": "https://github.com/ash-project/ash_postgres",
          "vendor": "ash-project",
          "modules": [
            "'Elixir.AshPostgres.DataLayer'"
          ],
          "product": "ash_postgres",
          "versions": [
            {
              "status": "affected",
              "version": "af0903f1380468bbe1b61fe65acb33772b5e24a5",
              "lessThan": "8aa81220c401cae412d21078d11b3519ea25d3a9",
              "versionType": "git"
            }
          ],
          "packageURL": "pkg:github/ash-project/ash_postgres",
          "packageName": "ash-project/ash_postgres",
          "programFiles": [
            "lib/data_layer.ex"
          ],
          "collectionURL": "https://github.com",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "'Elixir.AshPostgres.DataLayer':do_bulk_create/3"
            },
            {
              "name": "'Elixir.AshPostgres.DataLayer':upsert/4"
            },
            {
              "name": "'Elixir.AshPostgres.DataLayer':bulk_create/3"
            }
          ]
        }
      ],
      "modified": "2026-10-26T14:35:21.261Z",
      "provider": "cve",
      "references": [
        "https://github.com/ash-project/ash/security/advisories/GHSA-36hg-wwp2-fg8w",
        "https://cna.erlef.org/cves/CVE-2026-115635.html",
        "https://osv.dev/vulnerability/EEF-CVE-2026-115635",
        "https://github.com/ash-project/ash_postgres/commit/af0903f1380468bbe1b61fe65acb33772b5e24a5",
        "https://github.com/ash-project/ash_postgres/commit/8aa81220c401cae412d21078d11b3519ea25d3a9"
      ],
      "provider_metadata": {
        "adp": [
          {
            "title": "CISA ADP Vulnrichment",
            "metrics": [
              {
                "other": {
                  "type": "ssvc",
                  "content": {
                    "id": "CVE-2026-115635",
                    "role": "CISA Coordinator",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "version": "2.0.3",
                    "timestamp": "2026-10-26T14:29:19.217057Z"
                  }
                }
              }
            ],
            "providerMetadata": {
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP",
              "dateUpdated": "2026-10-26T14:35:21.261Z"
            }
          }
        ],
        "cna": {
          "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
          "shortName": "EEF",
          "dateUpdated": "2026-10-25T19:48:43.829Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-115635",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/containers/cna/metrics"
  },
  "source_id": "core-cve",
  "document_id": 311571,
  "published_at": "2026-10-25T19:48:43.829+00:00"
}