Discourse is an open-source discussion platform. Versions prior to 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 have two authorization issues in the chat direct message API. First, when creating a direct message channel or adding users to an existing one, the `target_groups` parameter was passed directly to the user resolution query without checking group or member visibility for the acting user.
An authenticated chat user could craft an API request with a known private/hidden group name and receive a channel containing that group's members, leaking their identities. Second, `can_chat?` only checked group membership, not the `chat_enabled` user preference. A chat-disabled user could create or query DM channels between other users via the direct messages API, potentially exposing private `last_message` content from the serialized channel response.
Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. No known workarounds are available.
Attack Parameters
Impact Assessment
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products 3
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Discourse Discourse
cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*
|
2026.1.0
|
2026.1.2
|
|
Discourse Discourse
cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*
|
2026.2.0
|
2026.2.1
|
|
Discourse Discourse
cpe:2.3:a:discourse:discourse:2026.3.0:*:*:*:latest:*:*:*
|
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