CVE-2026-82741 (GCVE-0-2026-82741)

Vulnerability from cvelistv5 – Published: 2026-09-01 03:33 – Updated: 2026-09-01 03:33
VLAI
Title
Ash.Type.Union with :map_with_tag does not force the tag on dump, enabling tag confusion
Summary
Improper Validation of Specified Type of Input vulnerability in ash-project ash lets an attacker confuse the stored type tag of an Ash.Type.Union value that uses storage: :map_with_tag, bypassing that member's validation and any tag-based authorization. For a union with storage: :map_with_tag, each member is identified in storage by a configured tag and tag_value. Ash.Type.Union.dump_to_native/2 (lib/ash/type/union.ex) did not force the configured tag when writing the value, so a tag carried in the submitted value was persisted verbatim. An attacker can therefore store a value whose data belongs to one member but whose tag names a different member. On read the value is re-selected by its tag and treated as the incompatible member (a type confusion), bypassing the real member's constraints and any logic or policy that branches on the union tag. The fix drops any incoming tag and forces the configured tag value on dump. This issue affects ash: from 2.14.18 before 3.32.2.
CWE
  • CWE-1287 - Improper Validation of Specified Type of Input
Assigner
Impacted products
Vendor Product Version CPE status
ash-project ash Affected: 2.14.18 , < 3.32.2 (semver)
    cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*
Create a notification for this product.
ash-project ash Affected: b0bd2d23d979e731610327636f51da4981fcef68 , < 8dbdaecd0f115f52e7c3f9a3e798617d6fbf5f7d (git)
    cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*
Create a notification for this product.
Show details on NVD website

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      "affected": [
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "\u0027Elixir.Ash.Type.Union\u0027"
          ],
          "packageName": "ash",
          "packageURL": "pkg:hex/ash",
          "product": "ash",
          "programFiles": [
            "lib/ash/type/union.ex"
          ],
          "programRoutines": [
            {
              "name": "\u0027Elixir.Ash.Type.Union\u0027:dump_to_native/2"
            }
          ],
          "repo": "https://github.com/ash-project/ash",
          "vendor": "ash-project",
          "versions": [
            {
              "lessThan": "3.32.2",
              "status": "affected",
              "version": "2.14.18",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "\u0027Elixir.Ash.Type.Union\u0027"
          ],
          "packageName": "ash-project/ash",
          "packageURL": "pkg:github/ash-project/ash",
          "product": "ash",
          "programFiles": [
            "lib/ash/type/union.ex"
          ],
          "programRoutines": [
            {
              "name": "\u0027Elixir.Ash.Type.Union\u0027:dump_to_native/2"
            }
          ],
          "repo": "https://github.com/ash-project/ash",
          "vendor": "ash-project",
          "versions": [
            {
              "lessThan": "8dbdaecd0f115f52e7c3f9a3e798617d6fbf5f7d",
              "status": "affected",
              "version": "b0bd2d23d979e731610327636f51da4981fcef68",
              "versionType": "git"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:ash-project:ash:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "3.32.2",
                  "versionStartIncluding": "2.14.18",
                  "vulnerable": true
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              "operator": "OR"
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          "operator": "AND"
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      ],
      "credits": [
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Zach Daniel / Ash Project"
        },
        {
          "lang": "en",
          "type": "coordinator",
          "value": "Jonatan M\u00e4nnchen / EEF"
        },
        {
          "lang": "en",
          "type": "reporter",
          "value": "Peter Ullrich"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "Peter Ullrich"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eImproper Validation of Specified Type of Input vulnerability in ash-project ash lets an attacker confuse the stored type tag of an \u003ccode\u003eAsh.Type.Union\u003c/code\u003e value that uses \u003ccode\u003estorage: :map_with_tag\u003c/code\u003e, bypassing that member\u0027s validation and any tag-based authorization.\u003c/p\u003e\n\u003cp\u003eFor a union with \u003ccode\u003estorage: :map_with_tag\u003c/code\u003e, each member is identified in storage by a configured \u003ccode\u003etag\u003c/code\u003e and \u003ccode\u003etag_value\u003c/code\u003e. \u003ccode\u003eAsh.Type.Union.dump_to_native/2\u003c/code\u003e (\u003ccode\u003elib/ash/type/union.ex\u003c/code\u003e) did not force the configured tag when writing the value, so a tag carried in the submitted value was persisted verbatim. An attacker can therefore store a value whose data belongs to one member but whose tag names a different member. On read the value is re-selected by its tag and treated as the incompatible member (a type confusion), bypassing the real member\u0027s constraints and any logic or policy that branches on the union tag. The fix drops any incoming tag and forces the configured tag value on dump.\u003c/p\u003e\n\u003cp\u003eThis issue affects ash: from 2.14.18 before 3.32.2.\u003c/p\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "Improper Validation of Specified Type of Input vulnerability in ash-project ash lets an attacker confuse the stored type tag of an `Ash.Type.Union` value that uses `storage: :map_with_tag`, bypassing that member\u0027s validation and any tag-based authorization.\n\nFor a union with `storage: :map_with_tag`, each member is identified in storage by a configured `tag` and `tag_value`. `Ash.Type.Union.dump_to_native/2` (`lib/ash/type/union.ex`) did not force the configured tag when writing the value, so a tag carried in the submitted value was persisted verbatim. An attacker can therefore store a value whose data belongs to one member but whose tag names a different member. On read the value is re-selected by its tag and treated as the incompatible member (a type confusion), bypassing the real member\u0027s constraints and any logic or policy that branches on the union tag. The fix drops any incoming tag and forces the configured tag value on dump.\n\nThis issue affects ash: from 2.14.18 before 3.32.2."
            }
          ],
          "value": "Improper Validation of Specified Type of Input vulnerability in ash-project ash lets an attacker confuse the stored type tag of an Ash.Type.Union value that uses storage: :map_with_tag, bypassing that member\u0027s validation and any tag-based authorization.\n\nFor a union with storage: :map_with_tag, each member is identified in storage by a configured tag and tag_value. Ash.Type.Union.dump_to_native/2 (lib/ash/type/union.ex) did not force the configured tag when writing the value, so a tag carried in the submitted value was persisted verbatim. An attacker can therefore store a value whose data belongs to one member but whose tag names a different member. On read the value is re-selected by its tag and treated as the incompatible member (a type confusion), bypassing the real member\u0027s constraints and any logic or policy that branches on the union tag. The fix drops any incoming tag and forces the configured tag value on dump.\n\nThis issue affects ash: from 2.14.18 before 3.32.2."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-153",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-153 Input Data Manipulation"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "LOCAL",
            "baseScore": 2.1,
            "baseSeverity": "LOW",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "LOW",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
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      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-1287",
              "description": "CWE-1287 Improper Validation of Specified Type of Input",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-01T03:33:03.442Z",
        "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "shortName": "EEF"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory",
            "related"
          ],
          "url": "https://github.com/ash-project/ash/security/advisories/GHSA-2mmm-gc86-7jgg"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://cna.erlef.org/cves/CVE-2026-82741.html"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://osv.dev/vulnerability/EEF-CVE-2026-82741"
        },
        {
          "tags": [
            "patch"
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          "url": "https://github.com/ash-project/ash/commit/8dbdaecd0f115f52e7c3f9a3e798617d6fbf5f7d"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "title": "Ash.Type.Union with :map_with_tag does not force the tag on dump, enabling tag confusion"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
    "assignerShortName": "EEF",
    "cveId": "CVE-2026-82741",
    "datePublished": "2026-09-01T03:33:03.442Z",
    "dateReserved": "2026-08-31T00:59:10.002Z",
    "dateUpdated": "2026-09-01T03:33:03.442Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}



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