Vulnerability Database

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Total vulnerabilities in the database

CVE-2026-55551

Improper Authorization

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.

  • Published: Oct 30, 2026
  • Updated: Nov 8, 2026
  • CVE: CVE-2026-55551
  • Severity: Medium
  • Exploit:
  • CISA KEV:

CVSS v3:

  • Severity: Medium
  • Score: 6.5
  • AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

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A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

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