MediumCVE-2021-20680

NEC Aterm devices: Cross-Site Scripting (XSS) (CVE-2021-20680)

Published 26.04.2021Sources: CVE.org

What is affected, what to do

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.

The available sources name no fixed version. Check the vendor guidance in the references below.

Affected: NEC Aterm devices eq Aterm WG1900HP2 firmware Ver.1.3.1 and earlier, Aterm WG1900HP firmware Ver.2.5.1 and earlier, Aterm WG1800HP4 firmware Ver.1.3...Aterm WG1900HP2 firmware Ver.1.3.1 and earlier, Aterm WG1900HP firmware Ver.2.5.1 and earlier, Aterm WG1800HP4 firmware Ver.1.3.

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Metrics

6.1

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v3

6.1

CVSS v3

Severity Medium on the scale from 0 to 10.

Source: CVE.org

0.8 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 56.6

Show all metrics

Severity: Medium
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 56.11 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: no public PoC known
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 6.1 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 6.1
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.8 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 56.6; High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 26.04.2021

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

Source: NVD (NIST), cvelistv5

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
NEC Corporation	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.`	—

Vendors and products

Affected operating systems

Affected operating systems

Other	nec	aterm_w1200ex-ms_firmware	—
Other	nec	aterm_w1200ex_firmware	—
Other	nec	aterm_w300p_firmware	—
Other	nec	aterm_w500p_firmware	—
Other	nec	aterm_wf300hp2_firmware	—
Other	nec	aterm_wf800hp_firmware	—
Other	nec	aterm_wg1200hp2_firmware	—
Other	nec	aterm_wg1200hp3_firmware	—
Other	nec	aterm_wg1200hp_firmware	—
Other	nec	aterm_wg1200hs2_firmware	—
Other	nec	aterm_wg1200hs3_firmware	—
Other	nec	aterm_wg1200hs_firmware	—
Other	nec	aterm_wg1800hp3_firmware	—
Other	nec	aterm_wg1800hp4_firmware	—
Other	nec	aterm_wg1900hp2_firmware	—
Other	nec	aterm_wg1900hp_firmware	—
Other	nec	aterm_wr8165n_firmware	—

References & sources

jpn.nec.comsecurity-info/secinfo/nv21-008.htmlx_refsource_MISC, Vendor advisory
jvn.jpen/jp/JVN67456944/index.htmlx_refsource_MISC, Third-party advisory

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