CVE-2026-72724 Discourse: Private Chat Threat Message Disclosure via Chat Onebox Channel/Threat ID Mismatch
An authenticated user can access private chat thread messages by mismatching channel and thread IDs in onebox requests, exposing sensitive data.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72724?
CVE-2026-72724 is a medium-severity missing authorization vulnerability in discourse, published on 10 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-639
Which versions are affected by CVE-2026-72724?
1 open source package ship an affected version, including discourse.
| Package | Affected | Fixed in |
|---|---|---|
discourse Bitnami | All versions | 2026.1.6, 2026.5.2, 2026.6.1 |
How do I fix CVE-2026-72724?
Upgrade discourse to a fixed version for your release line: 2026.1.6, 2026.5.2 or 2026.6.1.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-72724 being exploited?
There is no known exploitation of CVE-2026-72724 in the wild and no public exploit code.
Sources
Also known as BIT-discourse-2026-72724, GHSA-8g98-fvfc-9w48.