CVE intelligence and bounded remediation

CVE-2021-20137 — Gryphonconnect Gryphon Tower Firmware security vulnerability

Medium CVSS 6.1

A reflected cross-site scripting vulnerability exists in the url parameter of the /cgi-bin/luci/site_access/ page on the Gryphon Tower router's web interface. An attacker could exploit this issue by tricking a user into following a specially crafted link, granting the attacker javascript execution in the context of the victim's browser.

Severity
Medium
CVSS
6.1 (3.1)
Published
2021-12-09
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-79

Affected products

  • gryphonconnect / gryphon_tower_firmware

Matched remediation archetype

Cross-site scripting and unsafe browser output

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Trace reflected, stored, and DOM-derived untrusted values into HTML, attributes, URLs, styles, scripts, and client-side template sinks.
  • Identify affected origins, authenticated user roles, sensitive browser capabilities, and where content is shared across tenants.
  • Review framework escaping, rich-text sanitization, legacy templates, and client-side rendering paths.

Remediate safely

  • Use context-aware framework output encoding and safe DOM APIs; keep untrusted data out of executable contexts.
  • Sanitize intentionally supported markup with a maintained allowlist policy and validate URLs and attributes separately.
  • Update affected rendering components and add tests for every output context using inert sentinel markup.

Authoritative sources

Complete CVE record and remediation plan

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