CVE-2025-66488 MEDIUM

CVE-2025-66488: Discourse allows script execution in uploaded HTML/XML files on S3

Vendor Discourse
Product discourse
Weakness CWE-116
Published January 28, 2026
Last update January 28, 2026
View on NVD All CVEs

CVSS base score

4.6/10
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction Required
Confidentiality None
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L

What the vulnerability does

01Description

Discourse is an open source discussion platform. A vulnerability present in versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 affects anyone who uses S3 for uploads. While scripts may be executed, they will only be run in the context of the S3/CDN domain, with no site credentials. Versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 fix the issue. As a workaround, disallow html or xml files for uploads in authorized_extensions. For existing html xml uploads, site owners can consider deleting them.

Key dates

02Disclosure timeline

January 28, 2026 CVE published
January 28, 2026 Record updated