CVE-2024-45303: Discourse Calendar plugin event names susceptible to XSS

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-09-12 · updated 2026-06-17
Weakness: CWE-79

Description

Discourse Calendar plugin adds the ability to create a dynamic calendar in the first post of a topic to Discourse. Rendering event names can be susceptible to XSS attacks. This vulnerability only affects sites which have modified or disabled Discourse’s default Content Security Policy. The issue is patched in version 0.5 of the Discourse Calendar plugin.

Affected products

discourse-calendar: before 0.5 — fixed in 0.5

How to fix

Upgrade to a fixed version: discourse-calendar 0.5. Check the vendor advisory for mitigations.

References

https://github.com/discourse/discourse-calendar/commit/81e1c8e3c4c02276fb890da7e3f684259aeb685c
https://github.com/discourse/discourse-calendar/security/advisories/GHSA-rq37-8pf3-4xc8

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