NL Portal: IDOR allows any authenticated user to complete and tamper with another user's taak

published 2026-07-08 4 mo ago modified 2026-09-30 39 d ago also GHSA-6h3c-r723-7fx3 , EUVD-2026-76692

cvss: 8.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 28%
public exploits: 0; none known

NL Portal Backend Libraries provide backend components for Dutch government portals that interact with residents, customers, suppliers, and partner organizations. The `nl.nl-portal:taak` package from version 1.5.0 through 3.0.0 fails to verify ownership when processing the `submitTaakV2` GraphQL mutation, allowing an authenticated user who knows or guesses another user’s task ID to read its form data, overwrite its submitted data, and mark the task as completed. Version 3.0.1 contains a patch. As a workaround, block the `submitTaakV2` mutation at the API gateway or restrict the `/graphql` endpoint to trusted networks

Patch / fix

fixed in 1

maven nl.nl-portal:taak 3.0.1

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 55 d ago (2026-09-15)

Exploit prediction

0.35% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
GitHub	3.1	8.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

Affected packages

ecosystem	package	affected	fixed in
maven	nl.nl-portal:taak	>=1.5.0, <3.0.1	3.0.1

Affected products

nl-portal nl-portal-backend-libraries

Classification

Weakness

CWE-639 Authorization Bypass Through User-Controlled Key

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary