Discourse is an open source platform for community discussion. Without a rate limit on the POST /uploads endpoint, it makes it easier for an attacker to carry out a DoS attack on the server since creating an upload can be a resource intensive process. Do note that the impact varies from site to site as various site settings like max_image_size_kb, max_attachment_size_kb and max_image_megapixels will determine the amount of resources used when creating an upload.

The issue is patched in the latest stable, beta and tests-passed version of Discourse. Users are advised to upgrade. Users unable to upgrade should reduce max_image_size_kb, max_attachment_size_kb and max_image_megapixels as smaller uploads require less resources to process.

Alternatively, client_max_body_size can be reduced in Nginx to prevent large uploads from reaching the server.