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Vulnerability record · CVE-2019-9955 · published 22 April 2019

CVE-2019-9955: Zyxel atp200 firmware cross-site scripting vulnerability

Zyxel · Atp200 Firmware

On Zyxel ATP200, ATP500, ATP800, USG20-VPN, USG20W-VPN, USG40, USG40W, USG60, USG60W, USG110, USG210, USG310, USG1100, USG1900, USG2200-VPN, ZyWALL 110, ZyWALL 310, ZyWALL 1100 devices, the security firewall login page is vulnerable to Reflected XSS via the unsanitized 'mp_idx' parameter.

6.1 CVSS 3.0 Medium EPSS 21% · top 2.5% CWE-79 · Cross-site scripting
6.1CVSS 3.0 base score, v2 4.3
21%EPSS exploitation probability, 30 days
NoNot in CISA KEV
21Affected product versions listed by NVD
10References, 4 tagged exploit
17 Jun 2026Last modified by NVD

Description

On Zyxel ATP200, ATP500, ATP800, USG20-VPN, USG20W-VPN, USG40, USG40W, USG60, USG60W, USG110, USG210, USG310, USG1100, USG1900, USG2200-VPN, ZyWALL 110, ZyWALL 310, ZyWALL 1100 devices, the security firewall login page is vulnerable to Reflected XSS via the unsanitized 'mp_idx' parameter.

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products

21 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://packetstormsecurity.com/files/152525/Zyxel-ZyWall-Cross-Site-Scripting.html ExploitThird Party AdvisoryVDB Entry
http://seclists.org/fulldisclosure/2019/Apr/22 Mailing ListThird Party Advisory
https://www.exploit-db.com/exploits/46706/ ExploitThird Party AdvisoryVDB Entry
https://www.securitymetrics.com/blog/Zyxel-Devices-Vulnerable-Cross-Site-Scripting-Login-page PatchThird Party Advisory
https://www.zyxel.com/support/reflected-cross-site-scripting-vulnerability-of-firewalls.shtml Vendor Advisory
http://packetstormsecurity.com/files/152525/Zyxel-ZyWall-Cross-Site-Scripting.html ExploitThird Party AdvisoryVDB Entry
http://seclists.org/fulldisclosure/2019/Apr/22 Mailing ListThird Party Advisory
https://www.exploit-db.com/exploits/46706/ ExploitThird Party AdvisoryVDB Entry
https://www.securitymetrics.com/blog/Zyxel-Devices-Vulnerable-Cross-Site-Scripting-Login-page PatchThird Party Advisory
https://www.zyxel.com/support/reflected-cross-site-scripting-vulnerability-of-firewalls.shtml Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2019-9955), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.