CVE intelligence and bounded remediation

CVE-2021-47870 — GetSimple CMS My SMTP Contact Plugin 1.1.2 suffers from a Stored Cross-Site Scripting (XSS) vulnerability

Medium CVSS 5.4

GetSimple CMS My SMTP Contact Plugin 1.1.2 suffers from a Stored Cross-Site Scripting (XSS) vulnerability. The plugin attempts to sanitize user input using htmlspecialchars(), but this can be bypassed by passing dangerous characters as escaped hex bytes. This allows attackers to inject arbitrary client-side code that executes in the administrator's browser when visiting a malicious page.

Severity
Medium
CVSS
5.4 (3.1)
Published
2026-01-21
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-79

Affected products

  • get-simple / getsimplecms / 1.1.2

Matched remediation archetype

Cross-site scripting and unsafe browser output

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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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