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Vulnerability · Published Aug 10, 2026 · Assigned by GitHub_M

CVE-2026-72724Discourse: Private Chat Threat Message Disclosure via Chat Onebox Channel/Threat ID Mismatch

Medium 4.3

In plain English

A medium-severity authorization bypass via user-controlled key in discourse from discourse. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities).

Severity (CVSS 3.1)4.3Medium
Exploit odds (30 days)0.6%top 49.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

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.

Affected products (as reported)

VendorProductVersions
discourse discourse < 2026.1.6>= 2026.5.0-latest, < 2026.5.2>= 2026.6.0-latest, < 2026.6.1>= 2026.7.0-latest, < 2026.7.0

Weakness: CWE-639 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

References