Discourse onebox_handler.rb Chat Thread Disclosure before 2026.1.6
CVE-2026-72724 Published on August 10, 2026

Discourse: Private Chat Threat Message Disclosure via Chat Onebox Channel/Threat ID Mismatch
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.

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-72724 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
LOW
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
LOW
Integrity Impact:
NONE
Availability Impact:
NONE

Weakness Type

What is an Insecure Direct Object Reference / IDOR Vulnerability?

The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.

CVE-2026-72724 has been classified to as an Insecure Direct Object Reference / IDOR vulnerability or weakness.


Products Associated with CVE-2026-72724

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Discourse
 

Affected Versions

discourse: