CVE-2021-20712Network attack vector

WAN-to-LAN access via defective IPv6 firewall

Published Apr 26, 2021 · Updated Aug 3, 2024

Improper access control in NEC Aterm WG2600HS 1.5.1 and earlier and WX3000HP 1.1.2 and earlier allows remote attackers to reach LAN devices. The IPv6 firewall incorrectly permits WAN-side traffic to cross the router's WAN-to-LAN boundary instead of blocking access to protected devices. Exploitation requires traffic to traverse the affected IPv6 firewall, and the published impact is limited to unauthorized access to LAN-side devices.

CVSS severity5.3
Medium
EPSS probability0.80%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper access control in NEC Aterm WG2600HS 1.5.1 and earlier and WX3000HP 1.1.2 and earlier allows remote attackers to reach LAN devices. The IPv6 firewall incorrectly permits WAN-side traffic to cross the router's WAN-to-LAN boundary instead of blocking access to protected devices. Exploitation requires traffic to traverse the affected IPv6 firewall, and the published impact is limited to unauthorized access to LAN-side devices.

The record

CVE
CVE-2021-20712
Published
Apr 26, 2021
Updated
Aug 3, 2024
Vendor
NEC Platforms, Ltd.
Product
Aterm
Classifications
CWE-284, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Aterm WG2600HS firmware Ver1.5.1 and earlier, and Aterm WX3000HP firmware Ver1.1.2 and earlier

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

NEC Platforms, Ltd. · Atermversion=Aterm WG2600HS firmware Ver1.5.1 and earlier, and Aterm WX3000HP firmware Ver1.1.2 and earlier

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
5.3JPCERT/CCCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.0JPCERT/CCAV:N/AC:L/Au:N/C:P/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo