Description
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.
Problem types
CWE-770: Allocation of Resources Without Limits or Throttling
Product status
>= 2025.11.0-latest, < 2025.11.2
>= 2025.12.0-latest, 2025.12.1
>= 2026.1.0-latest, < 2026.1.0
References
github.com/...course/security/advisories/GHSA-vwjh-vrx9-9849