CVE intelligence and bounded remediation

CVE-2018-13879 — A reflected XSS issue was discovered in the registration form in Rocket.Chat before 0.66

Medium CVSS 5.4

A reflected XSS issue was discovered in the registration form in Rocket.Chat before 0.66. When one creates an account, the next step will ask for a username. This field will not save HTML control characters but an error will be displayed that shows the attempted username unescaped via packages/rocketchat-ui-login/client/username/username.js in packages/rocketchat-ui-login/client/username/username.html.

Severity
Medium
CVSS
5.4 (3.0)
Published
2018-07-11
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-79

Affected products

  • rocket.chat / rocket.chat

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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