Input validation error in Discourse - CVE-2026-33427
Published: July 1, 2026
Vulnerability identifier: #VU136139
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-33427
CWE-ID: CWE-20
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 conduct social engineering attacks against users.
The vulnerability exists due to improper input validation in the authorization page when displaying a redirect domain. A remote attacker can supply an attacker-controlled domain to conduct social engineering attacks against users.
How to mitigate CVE-2026-33427
Install security update from vendor's website.