CVE-2023-43658: Discourse Calendar

Medium severity, CVSS 6.1. EPSS: 0.5% chance of exploitation in the next 30 days.

dicourse-calendar is a plugin for the Discourse messaging platform which adds the ability to create a dynamic calendar in the first post of a topic. Improper escaping of event titles could lead to Cross-site Scripting (XSS) within the 'email preview' UI when a site has CSP disabled. Having CSP disabled is a non-default configuration, so the vast majority of sites are unaffected. This problem is resolved in the latest version of the discourse-calendar plugin. Users are advised to upgrade. Users unable to upgrade should ensure CSP is enabled on the forum.

Affected products

• Discourse Discourse Calendar: up to and including 2023-10-16

Published 2023-10-16. Last modified 2026-06-17.