CVE-2024-24827: No rate limits on POST /uploads endpoint in Discourse

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-03-15 · updated 2026-06-17
Weakness: CWE-400

Description

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.

Affected products

discourse: before 3.2.0; before 3.3.0 — fixed in 3.2.0, 3.3.0

How to fix

Upgrade to a fixed version: discourse 3.2.0, 3.3.0. Check the vendor advisory for mitigations.

References

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