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Medium severity · published Aug 10, 2026
CVE-2026-72724
Discourse: Private Chat Threat Message Disclosure via Chat Onebox Channel/Threat ID Mismatch
4.3
CVSS
0.6%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 50% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
DI
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 · source: vendor
Affected product
DI
discourse
discourse
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-72724
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-72724
github.com
https://github.com/discourse/discourse/commit/1276d7032af8803956c74ae87ccfd976938dcd75
github.com
https://github.com/discourse/discourse/commit/45ab6d54076de9ca4965888974d4416d5b48e83c
github.com
https://github.com/discourse/discourse/commit/49efe1d7f098f2ce7301908815a211cc9248270f
github.com
https://github.com/discourse/discourse/commit/dc54846f0754799591717b6018343e49524e41ce
github.com
https://github.com/discourse/discourse/pull/42091
github.com
https://github.com/discourse/discourse/pull/42092
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