Vulnerability-Lookup

CVE-2026-64643 (GCVE-0-2026-64643)

Vulnerability from cvelistv5 – Published: 2026-07-27 17:48 – Updated: 2026-07-27 18:21

Title

Next.js: Unauthenticated Disclosure of Internal Server Function endpoints

Summary

Next.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.

Severity

6.3 (Medium)


                        
                          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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-201 - Insertion of Sensitive Information Into Sent Data

Assigner

GitHub_M

References

5 references

URL	Tags
https://github.com/vercel/next.js/security/adviso…	x_refsource_CONFIRM
https://github.com/vercel/next.js/commit/1b0c3ae9…	x_refsource_MISC
https://github.com/vercel/next.js/commit/ff12a612…	x_refsource_MISC
https://github.com/vercel/next.js/releases/tag/v15.5.21	x_refsource_MISC
https://github.com/vercel/next.js/releases/tag/v16.2.11	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
vercel	next.js	Affected: >= 13.0.0, < 15.5.21 Affected: >= 16.0.0, < 16.2.11

Show details on NVD website

JSON

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{
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                "id": "CVE-2026-64643",
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      "title": "Next.js: Unauthenticated Disclosure of Internal Server Function endpoints"
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GHSA-955P-X3MX-JCVP

Vulnerability from github – Published: 2026-07-22 23:00 – Updated: 2026-07-22 23:00

Summary

Next.js: Unauthenticated disclosure of internal Server Function endpoints

Details

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.

Severity

6.3 (Medium)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "next"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "13.0.0"
            },
            {
              "fixed": "15.5.21"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "npm",
        "name": "next"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "16.0.0"
            },
            {
              "fixed": "16.2.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-64643"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-201"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-22T23:00:34Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Impact\n\nIn 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.\n\nServer Action IDs can be disclosed to unauthenticated users via publicly served client artifacts (for example, static chunks containing action references).\n\nAffected users are applications using App Router + Server Actions.  \n\nBy itself, this disclosure is typically a recon/enumeration primitive; however, it can increase risk when combined with other weaknesses.\n \n## Workarounds\n\nNever assume any authentication claims at the `use cache` or `use server` boundary. Always authenticate within the boundary.",
  "id": "GHSA-955p-x3mx-jcvp",
  "modified": "2026-07-22T23:00:34Z",
  "published": "2026-07-22T23:00:34Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/security/advisories/GHSA-955p-x3mx-jcvp"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/commit/1b0c3ae912a3ad925c60065cc8d55b070fa8bcd3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/commit/ff12a6124e1504f17b62de948b8a553fdecaef7b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/vercel/next.js"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/releases/tag/v15.5.21"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vercel/next.js/releases/tag/v16.2.11"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Next.js: Unauthenticated disclosure of internal Server Function endpoints"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

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