Improper access control in Discourse - #VU140002
Published: July 29, 2026
Vulnerability identifier: #VU140002
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: N/A
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Affected software:
Discourse
Discourse
Detailed vulnerability description
The vulnerability allows a remote user to disclose private chat thread messages.
The vulnerability exists due to improper access control in the onebox endpoint when handling onebox requests with a public chat channel ID paired with a private thread ID. A remote user can send a crafted onebox request to disclose private chat thread messages.
Remediation
Install security update from vendor's website.