CVE-2026-72724

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

MEDIUM
4.3
CVSS Score
Published: August 10, 2026 at 03:59 PM UTC
Updated: September 8, 2026 at 09:09 PM UTC
1 product affected across 1 vendorDiscourse

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Severity
MEDIUM4.3
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2026.1.6v < 2026.5.2v < 2026.6.1v < 2026.7.0
Affected range stops below 2026.1.6, so it looks safe — our inference, not a vendor statement
Affected range stops below 2026.5.2, so it looks safe — our inference, not a vendor statement
Affected range stops below 2026.6.1, so it looks safe — our inference, not a vendor statement
Affected range stops below 2026.7.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.3MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-639

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