nuts-node has JWT type confusion in v1 access token introspection that allows VP replay as access token

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.4 · CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS

• CVE-2026-41164: 0.08% estimated exploitation activity in the next 30 days; percentile 0.10 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The v1 access token introspection endpoint (/auth/v1/introspectaccesstoken) accepts any JWT signed by a key present on the node, without validating the JWT type, issuer-to-key binding, or required claims. This allows a Verifiable Presentation (VP) JWT to be replayed as an access token and receive an active: true introspection response. Background In the v1 auth flow (Nuts RFC003), access tokens are JWTs signed by the authorizer's key with: - iss = authorizer organization DID - sub = requester organization DID - service = purpose of use (e.g. "eOverdracht") - typ header = "JWT" (default, not explicitly set) Verifiable Presentations are also JWTs with typ: "JWT" (per W3C VC Data Model 1.1). The W3C VC Data Model 2.0 changed this to vp+jwt specifically to prevent this class of confusion attack (See Securing Verifiable Credentials using JOSE and COSE 3.1.1). Vulnerability details The introspection endpoint performs only standard JWT checks. It does not perform the following…

Published by the source

5 May 2026, 17:15 UTC

Last modified by the source

8 Jun 2026, 23:28 UTC

Source last checked

26 Oct 2026, 15:23 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-9hmg-827w-9rhj

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# Patch Next advisory brief: CVE-2026-41164

Advisory: nuts-node has JWT type confusion in v1 access token introspection that allows VP replay as access token
IDs: CVE-2026-41164, GHSA-9hmg-827w-9rhj
Record: https://patchnext.com/advisories/cve-2026-41164 (revision 1, source checked 26 Oct 2026, 15:23 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/nuts-foundation/nuts-node: affected <= 1.1.0

## Suggested inspection (read-only)
- Go github.com/nuts-foundation/nuts-node: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/nuts-foundation/nuts-node.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-9hmg-827w-9rhj (GitHub-reviewed advisory GHSA-9hmg-827w-9rhj lists affected ranges: Go github.com/nuts-foundation/nuts-node >=0 <=1.1.0)

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