PYSEC-2026-1252

### Impact

There are a number of CKAN plugins, including [XLoader](https://github.com/ckan/ckanext-xloader), [DataPusher](https://github.com/ckan/datapusher), [Resource proxy](https://docs.ckan.org/en/latest/maintaining/data-viewer.html#resource-proxy) and [ckanext-archiver](https://github.com/ckan/ckanext-archiver/), that work by downloading the contents of local or remote files in order to perform some actions with their contents (e.g. pushing to the DataStore, streaming contents or saving a local copy). All of them use the resource URL, and there are currently no checks to limit what URLs can be requested. This means that a malicious (or unaware) user can create a resource with a URL pointing to a place where they should not have access in order for one of the previous tools to retrieve it (known as a [Server Side Request Forgery](https://owasp.org/www-community/attacks/Server_Side_Request_Forgery)).

### Patches and Workarounds

Users wanting to protect against these kinds of attacks can use one or a combination of the following approaches:

* Use a separate HTTP proxy like [Squid](https://www.squid-cache.org/) that can be used to allow / disallow IPs, domains etc as needed, and make CKAN extensions aware of this setting via the [`ckan.download_proxy`](https://docs.ckan.org/en/latest/maintaining/configuration.html#ckan-download-proxy) config option. * Implement custom firewall rules to prevent access to restricted resources. * Use custom validators on the resource `url` field to block/allow certain domains or IPs.

All latest versions of the plugins linked above support the `ckan.download_proxy` settings. Support for this setting in the Resource Proxy plugin was included in CKAN 2.10.5 and 2.11.0

### References

* [Blog post](https://feeding.cloud.geek.nz/posts/restricting-outgoing-webapp-requests-using-squid-proxy/) provides more details on how to configure a Squid proxy to prevent these issues