CVE intelligence and bounded remediation

CVE-2021-42663 — Online Event Booking And Reservation System Project Online Event Bookin… security vulnerability

Medium CVSS 4.3

An HTML injection vulnerability exists in Sourcecodester Online Event Booking and Reservation System in PHP/MySQL via the msg parameter to /event-management/index.php. An attacker can leverage this vulnerability in order to change the visibility of the website. Once the target user clicks on a given link he will display the content of the HTML code of the attacker's choice.

Severity
Medium
CVSS
4.3 (3.1)
Published
2021-11-05
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-79

Affected products

  • online_event_booking_and_reservation_system_project / online_event_booking_and_reservation_system / 2.3.0

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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