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CVE-2019-9955· NVD / CVE Program· CNA mitre

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

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.

MediumCVSS 6.1 · v3.0—Proof of concept No fix recorded

Noroxi analysis

No Noroxi analysis for this record yet

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Published
Apr 22, 2019
Updated
Jun 16, 2026
EPSS
21.2% · 98th percentile
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Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
24 / 40 · 6.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
6 / 30 · 21.2%

Affected systems

VendorProduct
zyxelatp200 firmware
zyxelatp200
zyxelatp500 firmware
zyxelatp500
zyxelatp800 firmware
zyxelatp800
zyxelusg20-vpn firmware
zyxelusg20-vpn
zyxelusg20w-vpn firmware
zyxelusg20w-vpn
zyxelusg40 firmware
zyxelusg40

and 30 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • zyxel atp200 firmware4.31
  • zyxel atp500 firmware4.31
  • zyxel atp800 firmware4.31
  • zyxel usg110 firmware4.31
  • zyxel usg1100 firmware4.31
  • zyxel usg1900 firmware4.31
  • zyxel usg20-vpn firmware4.31
  • zyxel usg20w-vpn firmware4.31
  • zyxel usg210 firmware4.31
  • zyxel usg2200-vpn firmware4.31
  • zyxel usg310 firmware4.31
  • zyxel usg40 firmware4.31
  • zyxel usg40w firmware4.31
  • zyxel usg60 firmware4.31
  • zyxel usg60w firmware4.31
  • zyxel vpn100 firmwareall versions
  • zyxel vpn300 firmwareall versions
  • zyxel vpn50 firmwareall versions
  • zyxel zywall 110 firmware4.31
  • zyxel zywall 1100 firmware4.31

Same product

zyxel: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-27991The post-authentication command injection vulnerability in the CLI command of Zyxel ATP series firmware versions 4.32 through 5.35, USG FLEX
    35Monitor
  • CVE-2023-22918A post-authentication information exposure vulnerability in the CGI program of Zyxel ATP series firmware versions 4.32 through 5.35, USG FLE
    26Monitor
  • CVE-2023-27990The cross-site scripting (XSS) vulnerability in Zyxel ATP series firmware versions 4.32 through 5.35, USG FLEX series firmware versions 4.50
    19Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Exploit-DB entry ×1
  • Nuclei detection template ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Exploit-DB entrywebapps2019-04-16
Nuclei detection templateNuclei template CVE-2019-9955 —

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. First PoC-7 d
  2. Published
  3. TodaySep 30, 2026+2718 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
low · data or configuration can be modified
Availability
none

Impact can extend beyond the vulnerable component (scope changes).

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Changed
Confidentiality impact
Low
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS vector

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

nvd-primary

Root cause

User content is inserted into the page as HTML. The browser interprets the content as code rather than data.

The bug in code

The whole CWE-79 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
commentEl.innerHTML = comment.body;

Fixed

ts
commentEl.textContent = comment.body;

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records