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CVE-2026-55551

ZAC is an open-source, workflow-based Common Ground component for Dutch municipal case management

Risk score
42/100
CVSS
6.5 v3.1
Exploit chance (30 days)
0.3%
Published
30 Oct 2026

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What to know

What it is
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 hasAnyApplication…
Affected
See advisory
Fix
Upgrade the product to 5.2.0 or later.
Exploitation
No known exploitation

Why it is Yellow

  • CVSS 6.5 medium

References

Original description

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.

Last activity 30 Oct 2026. Patch Forecast updates every hour.