CVE-2026-72724
Description
Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, plugins/chat/lib/chat/onebox_handler.rb resolves Chat::Thread by route thread_id independently of the route channel_id before checking whether the user can preview the selected chat channel. An authenticated user can pair a public channel ID with a private thread ID in a /onebox.json request and obtain private thread message content. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
References
- https://github.com/discourse/discourse/commit/1276d7032af8803956c74ae87ccfd976938dcd75
- https://github.com/discourse/discourse/commit/45ab6d54076de9ca4965888974d4416d5b48e83c
- https://github.com/discourse/discourse/commit/49efe1d7f098f2ce7301908815a211cc9248270f
- https://github.com/discourse/discourse/commit/dc54846f0754799591717b6018343e49524e41ce
- https://github.com/discourse/discourse/pull/42091
- https://github.com/discourse/discourse/pull/42092
- https://github.com/discourse/discourse/pull/42093
- https://github.com/discourse/discourse/pull/42094
- https://github.com/discourse/discourse/security/advisories/GHSA-8g98-fvfc-9w48
CWEs
CWE-639
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.