ZAC: Missing per-zaaktype authorization on by-ID decision and process reads

{
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "cveMetadata": {
    "cveId": "CVE-2026-55551",
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "dateUpdated": "2026-10-30T16:48:51.352Z",
    "dateReserved": "2026-06-16T23:01:04.075Z",
    "datePublished": "2026-10-30T16:48:51.352Z",
    "state": "PUBLISHED"
  },
  "containers": {
    "cna": {
      "providerMetadata": {
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M",
        "dateUpdated": "2026-10-30T16:48:51.352Z"
      },
      "title": "ZAC: Missing per-zaaktype authorization on by-ID decision and process reads",
      "descriptions": [
        {
          "lang": "en",
          "value": "ZAC is an open-source, workflow-based Common Ground component for Dutch municipal case management. Prior to 5.2.0, by-id read endpoints in `src/main/kotlin/nl/info/zac/app/zaak/ZaakRestService.kt` omit `assertPolicy`(`policyService.readZaakRechten(zaak).lezen`) authorization. `RequestAuthorizationFilter` and `hasAnyApplicationRole` require only an application role on any zaaktype, not the target case's type, while `zaak-rechten.rego` enforces the actual `zaaktype_allowed` boundary only when invoked. An authenticated low-privileged municipal user who knows a case or decision UUID can use `GET /rest/zaken/besluit/zaakUuid/{uuid}` (`listBesluitenForZaakUUID`) to read decisions including types, dates, and free-text toelichting; `GET /rest/zaken/besluit/{uuid}/historie` (`listBesluitHistorie`) to read audit old/new values; and `GET /rest/zaken/{uuid}/process-diagram` (`downloadProcessDiagram`) to read BPMN workflow state across unauthorized zaaktypes. The advisory also identifies `zaak/{uuid}/afzender` (`listAfzendersVoorZaak`) as exposing zaaktype mailbox configuration without a policy check. The search/_zoek path is correctly authorization-filtered and is not part of this by-id read cluster. This issue is fixed in version 5.2.0."
        }
      ],
      "affected": [
        {
          "vendor": "infonl",
          "product": "dimpact-zaakafhandelcomponent",
          "versions": [
            {
              "version": "< 5.2.0",
              "status": "affected"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "CWE-285: Improper Authorization",
              "cweId": "CWE-285",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "lang": "en",
              "description": "CWE-639: Authorization Bypass Through User-Controlled Key",
              "cweId": "CWE-639",
              "type": "CWE"
            }
          ]
        }
      ],
      "references": [
        {
          "url": "https://github.com/infonl/dimpact-zaakafhandelcomponent/security/advisories/GHSA-cv9m-35q4-cxfm",
          "name": "https://github.com/infonl/dimpact-zaakafhandelcomponent/security/advisories/GHSA-cv9m-35q4-cxfm",
          "tags": [
            "x_refsource_CONFIRM"
          ]
        },
        {
          "url": "https://github.com/infonl/dimpact-zaakafhandelcomponent/pull/6225",
          "name": "https://github.com/infonl/dimpact-zaakafhandelcomponent/pull/6225",
          "tags": [
            "x_refsource_MISC"
          ]
        },
        {
          "url": "https://github.com/infonl/dimpact-zaakafhandelcomponent/pull/6229",
          "name": "https://github.com/infonl/dimpact-zaakafhandelcomponent/pull/6229",
          "tags": [
            "x_refsource_MISC"
          ]
        },
        {
          "url": "https://github.com/infonl/dimpact-zaakafhandelcomponent/commit/7b90586be658cec9fa5c98c0838636237f40931f",
          "name": "https://github.com/infonl/dimpact-zaakafhandelcomponent/commit/7b90586be658cec9fa5c98c0838636237f40931f",
          "tags": [
            "x_refsource_MISC"
          ]
        },
        {
          "url": "https://github.com/infonl/dimpact-zaakafhandelcomponent/commit/d050f247301a1bcfb867015725a693c540a06f5a",
          "name": "https://github.com/infonl/dimpact-zaakafhandelcomponent/commit/d050f247301a1bcfb867015725a693c540a06f5a",
          "tags": [
            "x_refsource_MISC"
          ]
        },
        {
          "url": "https://github.com/infonl/dimpact-zaakafhandelcomponent/releases/tag/v5.2.0",
          "name": "https://github.com/infonl/dimpact-zaakafhandelcomponent/releases/tag/v5.2.0",
          "tags": [
            "x_refsource_MISC"
          ]
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "version": "3.1",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
            "attackVector": "NETWORK",
            "attackComplexity": "LOW",
            "privilegesRequired": "LOW",
            "userInteraction": "NONE",
            "scope": "UNCHANGED",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "availabilityImpact": "NONE",
            "baseScore": 6.5,
            "baseSeverity": "MEDIUM"
          }
        }
      ]
    }
  }
}