---
id: CVE-2026-64643
aliases:
  - GHSA-955p-x3mx-jcvp
title: 'Next.js: Unauthenticated disclosure of internal Server Function endpoints'
summary: 'Next.js: Unauthenticated disclosure of internal Server Function endpoints'
severity: medium
cwe:
  - CWE-201
vendor: next
product: next
ecosystem: npm
affected:
  - 'next >= 13.0.0, < 15.5.21'
  - 'next >= 16.0.0, < 16.2.11'
patched:
  - next 15.5.21
  - next 16.2.11
published: '2026-07-22'
updated: '2026-07-22'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-955p-x3mx-jcvp'
references:
  - url: 'https://github.com/vercel/next.js/security/advisories/GHSA-955p-x3mx-jcvp'
  - url: >-
      https://github.com/vercel/next.js/commit/1b0c3ae912a3ad925c60065cc8d55b070fa8bcd3
  - url: >-
      https://github.com/vercel/next.js/commit/ff12a6124e1504f17b62de948b8a553fdecaef7b
  - url: 'https://github.com/vercel/next.js/releases/tag/v15.5.21'
  - url: 'https://github.com/vercel/next.js/releases/tag/v16.2.11'
  - url: 'https://github.com/advisories/GHSA-955p-x3mx-jcvp'
tags:
  - ghsa
  - npm
ingestedAt: '2026-07-22T23:07:32.263Z'
epss: 0.00516
epssPercentile: 0.42957
---

## Overview

## Impact

In Next.js applications using App Router, Server Actions (`use server`) or `use cache` endpoints can be disclosed bypassing any authentication on the pages where these endpoints are usually used.

Server Action IDs can be disclosed to unauthenticated users via publicly served client artifacts (for example, static chunks containing action references).

Affected users are applications using App Router + Server Actions.  

By itself, this disclosure is typically a recon/enumeration primitive; however, it can increase risk when combined with other weaknesses.
 
## Workarounds

Never assume any authentication claims at the `use cache` or `use server` boundary. Always authenticate within the boundary.

## Affected packages

- `next >= 13.0.0, < 15.5.21`
- `next >= 16.0.0, < 16.2.11`

## Remediation

Upgrade to a patched release:

- `next 15.5.21`
- `next 16.2.11`