CVE intelligence and bounded remediation

CVE-2021-24535 — Light Messages Project Light Messages security vulnerability

Medium CVSS 6.1

The Light Messages WordPress plugin through 1.0 is lacking CSRF check when updating it's settings, and is not sanitising its Message Content in them (even with the unfiltered_html disallowed). As a result, an attacker could make a logged in admin update the settings to arbitrary values, and set a Cross-Site Scripting payload in the Message Content. Depending on the options set, the XSS payload can be triggered either in the backend only (in the plugin's settings), or both frontend and backend.

Severity
Medium
CVSS
6.1 (3.1)
Published
2021-08-16
CISA KEV
Not currently listed
Ecosystem
php/wordpress
Weaknesses
CWE-79, CWE-352

Affected products

  • light_messages_project / light_messages

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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