CVE intelligence and bounded remediation

CVE-2021-34821 — Cross Site Scripting (XSS) vulnerability exists in AAT Novus Management System through 1.51.2

Medium CVSS 6.1

Cross Site Scripting (XSS) vulnerability exists in AAT Novus Management System through 1.51.2. The WebUI has wrong HTTP 404 error handling implemented. A remote, unauthenticated attacker may be able to exploit the issue by sending malicious HTTP requests to non-existing URIs. The value of the URL path filename is copied into the HTML document as plain text tags.

Severity
Medium
CVSS
6.1 (3.1)
Published
2021-07-19
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-79

Affected products

  • aat / novus_management_system

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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