CVE-2025-53640: Indico vulnerable to user enumeration via API endpoint

Impact 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.

[!TIP] If your instance allows everyone to create a user account, and you wish to truly restrict access to these user details, consider restricting user search to managers. You can find details on the newly introduced indico.conf setting ALLOWPUBLICUSERSEARCH in our documentation.

Patches You should to update to Indico 3.3.7 as soon as possible. See the docs for instructions on how to update.

Workarounds 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.

For more information If you have any questions or comments about this advisory:

- Open a thread in our forum - Email us privately at indico-team@cern.ch

Credits This vulnerability was identified during a security assessment conducted as part of the Red Team Residency Program at RNP (Rede Nacional de Ensino e Pesquisa). The research and testing were performed by a security researcher working under RNP’s authorization and coordination. Special acknowledgment goes to the RNP Security Team, which provided the infrastructure, methodology, and ethical oversight for this work.