What the vulnerability does
01Description
Discourse is an open source discussion platform. In versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0, authenticated users can submit crafted payloads to /drafts.json that cause O(n^2) processing in Base62.decode, tying up workers for 35-60 seconds per request. This affects all users as the shared worker pool becomes exhausted. This issue is patched in versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0. Lowering the max_draft_length site setting reduces attack surface but does not fully mitigate the issue, as payloads under the limit can still trigger the slow code path.
