PT-2026-63558 · Npm · Next

CVE-2026-64643 · Published 2026-07-22 · Updated 2026-07-22

OSV

CVSS v4.0

6.3

Medium

Base vector

AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

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.

Fix

Weakness Enumeration

CWE-201

Related Identifiers

CVE-2026-64643

GHSA-955P-X3MX-JCVP

Affected Products

Next

References · 7

• https://osv.dev/vulnerability/GHSA-955p-x3mx-jcvp · Vendor Advisory
• https://github.com/vercel/next.js/commit/ff12a6124e1504f17b62de948b8a553fdecaef7b · Note
• https://github.com/vercel/next.js/releases/tag/v16.2.11 · Note
• https://github.com/vercel/next.js · Note
• https://github.com/vercel/next.js/security/advisories/GHSA-955p-x3mx-jcvp · Note
• https://github.com/vercel/next.js/commit/1b0c3ae912a3ad925c60065cc8d55b070fa8bcd3 · Note
• https://github.com/vercel/next.js/releases/tag/v15.5.21 · Note