Cyber Resilience

CVE-2021-20855

Medium

Published: 01 December 2021

Published
01 December 2021
Modified
21 November 2024
KEV Added
—
Patch
—
CVSS Score v3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
EPSS Score 0.0021 43.4th percentile
Risk Priority 11 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-20855 is a medium-severity Cross-site Scripting (CWE-79) vulnerability in Elecom Wrh-733Gbk Firmware. Its CVSS base score is 5.4 (Medium).

Operationally, ranked at the 43.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

Cross-site scripting vulnerability in ELECOM LAN routers (WRH-733GBK firmware v1.02.9 and prior and WRH-733GWH firmware v1.02.9 and prior) allows a remote authenticated attacker to inject an arbitrary script via unspecified vectors.

CWE(s)
CWE-79

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

elecom
wrh-733gbk firmware
≤ 1.02.9
elecom
wrh-733gwh firmware
≤ 1.02.9

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

CA-8 Penetration Testing
addresses: CWE-79

Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.

SI-10 Information Input Validation
addresses: CWE-79

Validates web inputs to reject script-related content that could produce XSS.

SI-15 Information Output Filtering
addresses: CWE-79

Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.

References