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Fencer Intel
medium 6.1

CVE-2019-9955 json

On Zyxel ATP200, ATP500, ATP800, USG20-VPN, USG20W-VPN, USG40, USG40W, USG60, USG60W, USG110, USG210, USG310, USG1100, USG1900, USG2200-VPN…

published 7y ago modified 4mo ago also EUVD-2019-19309

cvss
6.1
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
21.2%
EPSS 21.2% chance of exploitation in 30 days, percentile 97%
public exploits
1
Exploit-DB, plus a Nuclei check

Summary

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.

Patch / fix

Is CVE-2019-9955 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Timeline

  1. First public exploit (EDB-46706)
  2. Published

Exploit prediction

21.18% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • EDB-46706 Zyxel ZyWall 310 / ZyWall 110 / USG1900 / ATP500 / USG40 - Login Page Cross-Site Scripting webapps, 2019-04-16
  • Nuclei template Zyxel - Cross-Site Scripting nuclei detection template
  • packetstormsecurity.com http://packetstormsecurity.com/files/152525/Zyxel-ZyWall-Cross-Site-Scripting.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 6.1 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.