VulnTideExploited vulnerabilities, by vendor. Data as of .
Not in CISA KEVReported exploited: VulnCheck KEV since Published CVSS 9.8 criticalEPSS 71% probability of exploitation in 30 days
Zyxel

CVE-2021-4039: A command injection vulnerability in the web interface of the Zyxel NWA-1100-NH firmware could allow an attacker to e…

Is it exploited?

Reported, not confirmed by CISA. VulnCheck KEV lists it as exploited in the wild. CISA has not added it to its Known Exploited Vulnerabilities catalog as of .

VulnCheck KEV lists it since . It cites 3 public reports, the first from .

How likely is exploitation in the next 30 days?
71%

EPSS score, percentile 99.4 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?
9.8 Critical

CVSS v3.1 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected

  • 2.12(AASI.0)C0

Versions by product

Source: CISA KEV 2026.10.29, as of ; VulnCheck KEV, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.

Description

A command injection vulnerability in the web interface of the Zyxel NWA-1100-NH firmware could allow an attacker to execute arbitrary OS commands on the device.

Source: CVE List, as of . About the data.

What to do

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

Versions by product, as listed in the CVE record (1 product)
Zyxel NWA1100-NH firmware
StatusVersions
Affected2.12(AASI.0)C0

Source: CVE List, as of . About the data.

Weakness

CWE-78
  • CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.

Timeline

DateEvent
CVE record published
CVE record last updated

References

2

Known exploited Zyxel vulnerabilities

  • CVE-2026-7273: Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability (added )
  • CVE-2024-40890: Zyxel DSL CPE OS Command Injection Vulnerability (added )
  • CVE-2024-40891: Zyxel DSL CPE OS Command Injection Vulnerability (added )
  • CVE-2024-11667: Zyxel Multiple Firewalls Path Traversal Vulnerability (added )
  • CVE-2017-6884: Zyxel EMG2926 Routers Command Injection Vulnerability (added )