Is there a public exploit for CVE-2026-55551?

No public exploit for CVE-2026-55551 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-55551?

CVE-2026-55551 scores CVSS 6.5 (v3.1), rated medium.

6.5 Medium

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

CVE-2026-55551

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 zaaktypeallowed 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…

Assessment

CVSS: 6.5 (v3.1)
Severity: Medium
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 30 October 2026
Last updated: 30 October 2026
Weakness: CWE-285, CWE-639
Assigner: security-advisories@github.com

CVSS vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

At the source

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