CVE-2019-9955
On Zyxel ATP200, ATP500, ATP800, USG20-VPN, USG20W-VPN, USG40, USG40W, USG60, USG60W, USG110,...
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2019-9955- CVSS 3.0
- 6.1 Medium
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - CVSS 2.0
- 4.3 Medium
AV:N/AC:M/Au:N/C:N/I:P/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2019-9955- Updated
- 2026-11-02
EUVDEUVD-2019-19309 No score
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.
- Record
EUVD-2019-19309- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-9r2m-gm27-q4jp
On Zyxel ATP200, ATP500, ATP800, USG20-VPN, USG20W-VPN, USG40, USG40W, USG60, USG60W, USG110,...
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.
- Record
GHSA-9r2m-gm27-q4jp- CVSS 3.0
- 6.1 Medium
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
Affected products
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| Exploit-DB | Zyxel ZyWall 310 / ZyWall 110 / USG1900 / ATP500 / USG40 - Login Page Cross-Site Scripting | 2019-04-16 |
| Nuclei | Zyxel - Cross-Site Scripting |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, Exploit-DB, GitHub Advisories, Nuclei, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2019-9955 is a medium vulnerability (CVSS 6.1) in Zyxel Atp200 Firmware, published April 22, 2019. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 21.2%, the 97th percentile. No source names a fixed version.
References
securitymetrics.com/blog/Zyxel-Devices-Vulnerable-Cross-Site-Scripting-Login-page
seclists.org/fulldisclosure/2019/Apr/22
exploit-db.com/exploits/46706
packetstormsecurity.com/files/152525/Zyxel-ZyWall-Cross-Site-Scripting.html
zyxel.com/support/reflected-cross-site-scripting-vulnerability-of-firewalls.shtml
nvd.nist.gov/vuln/detail/CVE-2019-9955
github.com/advisories/GHSA-9r2m-gm27-q4jp