CVE intelligence and bounded remediation

CVE-2021-42078 — Php Event Calendar Project Php Event Calendar security vulnerability

Medium CVSS 6.1

PHP Event Calendar through 2021-11-04 allows persistent cross-site scripting (XSS), as demonstrated by the /server/ajax/events_manager.php title parameter. This can be exploited by an adversary in multiple ways, e.g., to perform actions on the page in the context of other users, or to deface the site.

Severity
Medium
CVSS
6.1 (3.1)
Published
2021-11-08
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-79

Affected products

  • php_event_calendar_project / php_event_calendar / 2021-11-04

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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