Next.js: Unauthenticated Disclosure of Internal Server Function endpoints

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-64643
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-27 18:16:59 UTC
Updated2026-07-27 19:17:21 UTC
DescriptionNext.js is a React framework for building full-stack web applications. In versions 12.0.0 through 15.5.20 and 16.0.0 through 16.2.10, 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 and Server Actions. By itself, this disclosure is typically a recon/enumeration primitive; however, it can increase risk when combined with other weaknesses. This issue has been fixed in versions 15.5.21 and 16.2.11.

Risk And Classification

Primary CVSS: v4.0 6.3 MEDIUM from [email protected]

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-201 | CWE-201 CWE-201: Insertion of Sensitive Information Into Sent Data

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary6.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/C...
4.0CNADECLARED6.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Vercel Next.js affected >= 13.0.0, < 15.5.21 Not specified
CNA Vercel Next.js affected >= 16.0.0, < 16.2.11 Not specified

References

ReferenceSourceLinkTags
github.com/vercel/next.js/releases/tag/v16.2.11 [email protected] github.com
github.com/vercel/next.js/releases/tag/v15.5.21 [email protected] github.com
github.com/vercel/next.js/security/advisories/GHSA-955p-x3mx-jcvp [email protected] github.com
github.com/vercel/next.js/commit/ff12a6124e1504f17b62de948b8a553fdecaef7b [email protected] github.com
github.com/vercel/next.js/commit/1b0c3ae912a3ad925c60065cc8d55b070fa8bcd3 [email protected] github.com
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