Indico vulnerable to user enumeration via API endpoint

Vulnerability Description

Indico is an event management system that uses Flask-Multipass, a multi-backend authentication system for Flask. Starting in version 2.2 and prior to version 3.3.7, an endpoint used to display details of users listed in certain fields (such as ACLs) could be misused to dump basic user details (such as name, affiliation and email) in bulk. Version 3.3.7 fixes the issue. Owners of instances that allow everyone to create a user account, who wish to truly restrict access to these user details, should consider restricting user search to managers. As a workaround, it is possible to restrict access to the affected endpoints (e.g. in the webserver config), but doing so would break certain form fields which could no longer show the details of the users listed in those fields, so upgrading instead is highly recommended.

References

• https://github.com/indico/indico/security/advisories/GHSA-q28v-664f-q6wj
• https://docs.getindico.io/en/stable/config/settings/#ALLOW_PUBLIC_USER_SEARCH
• https://docs.getindico.io/en/stable/installation/upgrade
• https://github.com/indico/indico/releases/tag/v3.3.7