Discourse: Hidden reply-to post raw can be disclosed through AI explain prompts
Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.4, 2026.3.0-latest to before 2026.3.1, and 2026.4.0-latest to before 2026.4.1, the AI "explain" helper only checks can_see? on the post being explained, not its reply_to_post, so any authenticated user with access to the AI helper could read the raw contents of a hidden parent post by invoking "Explain" on a reply to it. This issue has been patched in versions 2026.1.4, 2026.3.1, 2026.4.1, and 2026.5.0-latest.1.
Problem Types
| Type | CWE ID | Description |
|---|
| CWE | CWE-200 | CWE-200: Exposure of Sensitive Information to an Unauthorized Actor |
Type: CWE
Description: CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
Metrics
| Version | Base score | Base severity | Vector |
|---|
| 3.1 | 4.3 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N |
Version: 3.1
Base score: 4.3
Base severity: MEDIUM
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N