Authorization bypass through user-controlled key in Discourse - CVE-2026-26265
Published: July 1, 2026
Vulnerability identifier: #VU136122
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-26265
CWE-ID: CWE-639
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Civilized Discourse Construction Kit, Inc.
Affected software:
Discourse
Discourse
Detailed vulnerability description
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to improper access control in the directory items endpoint when handling requests with the user_field_ids parameter. A remote attacker can send a specially crafted request to disclose sensitive information.
The issue exposes private user field values for users in the directory, including fields intended to remain non-public.
How to mitigate CVE-2026-26265
Install security update from vendor's website.