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Not in CISA KEV
HIGH severity

CVE-2026-49464

HIGH

CVE-2026-49464 is a high-severity (CVSS 8.1) vulnerability in nl.nl-portal:taak. O3 Security confirms whether CVE-2026-49464 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

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

Published
Jul 8, 2026
Updated
Jul 8, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Jul 8, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected
☕nl.nl-portal:taak

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Impact

In versions from 1.5.0 up to and including 3.0.0, any authenticated portal user could complete and tamper with another user's open task by submitting it on their behalf. The task submission endpoint accepted a task ID and a payload, but it never checked whether the task actually belonged to the user making the call.

An attacker who held a valid login (a normal burger OAuth token) and who knew or guessed another user's task ID could:

  • Mark someone else's task as completed.
  • Overwrite the data submitted with that task — the verzonden_data — with arbitrary input of their choosing.
  • Receive the full task back in the GraphQL response, including the form data that the legitimate owner had already entered. This leaks personal data belonging to the original user.

Functionally this means a malicious authenticated user could submit and alter forms in any other user's name, while at the same time reading what that user had previously filled in. Both the integrity of submitted data and the confidentiality of form contents are affected.

The vulnerable code was introduced together with the Taak V2 implementation (commit bb1c1ecf, 2024-06-04) and first shipped in the 1.5.x release line. Earlier 1.x releases did not contain this resolver.

Patches

Upgrade to 3.0.1 or later.

Fix commit: 8e699add — "Add auth check for task submission".

Workarounds

Until the upgrade is applied, block the submitTaakV2 GraphQL mutation at the API gateway, or restrict the /graphql endpoint to trusted networks.

Technical details

The resolver nl.nlportal.zgw.taak.service.TaakService.submitTaakV2(id, submission, authentication) fetched the task object by UUID and immediately transitioned it to the AFGEROND state, writing record.data.portaalformulier.verzondenData from caller-supplied input. No check verified that the task's identificatie matched the authenticated burger.

The fix adds a call to a new isAuthorizedForTaak(authentication, objectsApiTask) before the status change. The check compares identificatie.type and identificatie.value against the authenticated principal and validates the task's eigenaar for bedrijf machtigingen.

Credits

Discovered during the nl-portal-backend-libraries penetration testing engagement (phase 1, May 2026). Vendor attribution to be added before publication.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
☕Mavennl.nl-portal:taak≥ 1.5.0&&< 3.0.13.0.1

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nl.nl-portal:taak. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update nl.nl-portal:taak to 3.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-49464 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether CVE-2026-49464 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-49464. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Impact In versions from 1.5.0 up to and including 3.0.0, any authenticated portal user could complete and tamper with another user's open task by submitting it on their behalf. The task submission endpoint accepted a task ID and a payload, but it never checked whether the task actually belonged to the user making the call. An attacker who held a valid login (a normal `burger` OAuth token) and who knew or guessed another user's task ID could: - Mark someone else's task as completed. - Overwrite the data submitted with that task — the `verzonden_data` — with arbitrary input of their choosi
O3 Security · Impact-Aware SCA

Is CVE-2026-49464 in your dependencies?

O3 detects CVE-2026-49464 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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