CVE-2024-21641: Flarum

Medium severity, CVSS 4.7. EPSS: 1.1% chance of exploitation in the next 30 days.

Flarum is open source discussion platform software. Prior to version 1.8.5, the Flarum `/logout` route includes a redirect parameter that allows any third party to redirect users from a (trusted) domain of the Flarum installation to redirect to any link. For logged-in users, the logout must be confirmed. Guests are immediately redirected. This could be used by spammers to redirect to a web address using a trusted domain of a running Flarum installation. The vulnerability has been fixed and published as flarum/core v1.8.5. As a workaround, some extensions modifying the logout route can remedy this issue if their implementation is safe.

Affected products

• Flarum Flarum: before 1.8.5 (fixed in 1.8.5)

Published 2024-01-05. Last modified 2026-06-17.