Flarum's logout Route allows open redirects
Date: 2024-01
Affected: composer/flarum/framework, composer/flarum/core
Attack vector: other
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2024-21641
CWE: CWE-601
CVSS: 6.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N)

### Impact 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. Sample: `example.com/logout?return=https://google.com`. 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. Some ecosystem extensions modifying the logout route have already been affected. Sample: https://discuss.flarum.org/d/22229-premium-wordpress-integration/526 ### Patches The vulnerability has been fixed and published as flarum/core v1.8.5. All communities running Flarum should upgrade as soon as possible to v1.8.5 using: `composer update --prefer-dist --no-dev -a -W` You can then confirm you run the latest version using: `composer show flarum/core` ### Workarounds Some extensions modifying the logout route can remedy this issue if their implementation is safe. In any case we recommend updating to 1.8.5. ### References For any questions or comments on this vulnerability, please visit https://discuss.flarum.org/ For support questions, create a discussion at https://discuss.flarum.org/t/support. A reminder that if you ever become aware of a security issue in Flarum, please report it to us privately by emailing [security@flarum.org](mailto:security@flarum.org), and we will address it promptly.


Mitigations:

Architectural layers (MAESTRO):