HOMEVULNERABILITIESCVE-2021-20680
MEDIUM

CVE-2021-20680

CWE-79Published: April 26, 2021· Updated: Jun 17, 2026

6.1
CVSS v3.1

Official Description

Cross-site scripting vulnerability in NEC Aterm devices (Aterm WG1900HP2 firmware Ver.1.3.1 and earlier, Aterm WG1900HP firmware Ver.2.5.1 and earlier, Aterm WG1800HP4 firmware Ver.1.3.1 and earlier, Aterm WG1800HP3 firmware Ver.1.5.1 and earlier, Aterm WG1200HS2 firmware Ver.2.5.0 and earlier, Aterm WG1200HP3 firmware Ver.1.3.1 and earlier, Aterm WG1200HP2 firmware Ver.2.5.0 and earlier, Aterm W1200EX firmware Ver.1.3.1 and earlier, Aterm W1200EX-MS firmware Ver.1.3.1 and earlier, Aterm WG1200HS firmware all versions Aterm WG1200HP firmware all versions Aterm WF800HP firmware all versions Aterm WF300HP2 firmware all versions Aterm WR8165N firmware all versions Aterm W500P firmware all versions, and Aterm W300P firmware all versions) allows remote attackers to inject arbitrary script or HTML via unspecified vectors.

NVD Source

Technical Analysis

CVE-2021-20680 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.

From a weakness classification perspective (CWE-79): Cross-site scripting (XSS) vulnerabilities allow attackers to inject malicious scripts into web pages viewed by other users.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionRequired
ScopeChanged
Impact
ConfidentialityLow
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected Vendors & Products

nec34 product(s)
aterm wg1900hp2 firmwareaterm wg1900hp2aterm wg1900hp firmwareaterm wg1900hpaterm wg1800hp4 firmwareaterm wg1800hp4aterm wg1800hp3 firmwareaterm wg1800hp3aterm wg1200hs3 firmwareaterm wg1200hs3aterm wg1200hs2 firmwareaterm wg1200hs2+22
Source: NVD CPE · 34 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://jpn.nec.com/security-info/secinfo/nv21-008.html
ADVISORYhttps://jvn.jp/en/jp/JVN67456944/index.html
ADVISORYhttps://jpn.nec.com/security-info/secinfo/nv21-008.html
ADVISORYhttps://jvn.jp/en/jp/JVN67456944/index.html

All References (4)

→
https://jpn.nec.com/security-info/secinfo/nv21-008.htmlVendor Advisory
→
https://jvn.jp/en/jp/JVN67456944/index.htmlThird Party Advisory
→
https://jpn.nec.com/security-info/secinfo/nv21-008.htmlVendor Advisory
→
https://jvn.jp/en/jp/JVN67456944/index.htmlThird Party Advisory

Quick Facts

CVE IDCVE-2021-20680
CVSS Score6.1 / 10
SeverityMEDIUM
WeaknessCWE-79
CISA KEVNo
Affected1 vendor(s)
PublishedApr 26, 2021

Related CVEs (CWE-79)

CVE-2025-49410
10.0
CVE-2021-32671
10.0
CVE-2011-3046
10.0
CVE-2024-6886
10.0
CVE-2023-0776
10.0
CVE-2026-50551
9.9

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-20680 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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