Which products and versions are affected by CVE-2021-4039?

Affected: NWA1100-NH firmware (Zyxel) versions >= 2.12(AASI.0)C0. The full list is in the CVE brief.

Is CVE-2021-4039 being exploited in the wild?

It is exploited in the wild, listed in Industry KEV feed since May 26, 2022.

Is CVE-2021-4039 in the CISA KEV catalog?

No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.

Is there a public exploit for CVE-2021-4039?

Public exploit code is available.

Is there a fix for CVE-2021-4039?

Fixed versions are available, including NWA1100-NH firmware 2.12\(aasi.3\)c0.

How urgently should CVE-2021-4039 be patched?

Brandefense priority: patch immediately, because it is listed as exploited in the wild.

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Vulnerability Intelligence

CVE-2021-4039

CriticalExploitedPublic exploit

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.

Published Mar 2, 2022 · Updated Aug 3, 2024

Key Facts

Patch immediately

CVE-2021-4039 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting NWA1100-NH firmware (Zyxel).
It is exploited in the wild, listed in Industry KEV feed since May 26, 2022. Public exploit code is available.
EPSS estimates a 71% probability of exploitation in the next 30 days.
Fixed versions are available, including NWA1100-NH firmware 2.12\(aasi.3\)c0.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

CVSS v3.1

9.8

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS (30-day exploit likelihood)

71%

Higher than 99.4% of all scored CVEs

Exploited in the wild

Yes

1 catalog listing

Public exploit code

Available

Proof-of-concept or weaponized module

Get the full CVE-2021-4039 brief as a PDF

Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.

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.

Known-Exploited Catalog Listings

Catalog	Added	Remediation due	Ransomware use
Industry KEV feed	May 26, 2022	n/a	Not reported

Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

Affected Products

2 affected entries in total

Product	Affected versions	Fixed in
NWA1100-NH firmwareZyxel	>= 2.12(AASI.0)C0	2.12\(aasi.3\)c0

Patched Releases

NWA1100-NH firmware

2.12\(aasi.3\)c0

Timeline

Publicly disclosed
Mar 2, 2022
Added to Industry KEV feed
May 26, 2022
Last updated
Aug 3, 2024

Weakness Type

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

References

5 more references in the full CVE brief

FAQ

Common Questions.

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.
Affected: NWA1100-NH firmware (Zyxel) versions >= 2.12(AASI.0)C0. The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed since May 26, 2022.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including NWA1100-NH firmware 2.12\(aasi.3\)c0.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.

Is CVE-2021-4039 Running On Your Attack Surface?

Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.