CVE-2025-66488
January 28, 2026
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.
Affected Packages
https://github.com/discourse/discourse.git (GITHUB):
Affected version(s) >=v0.8.0 <v3.5.4Fix Suggestion:
Update to version v3.5.4https://github.com/discourse/discourse.git (GITHUB):
Affected version(s) >=v2025.11.0 <v2025.11.2Fix Suggestion:
Update to version v2025.11.2https://github.com/discourse/discourse.git (GITHUB):
Affected version(s) >=v2026.1.0 <v2026.1.0Fix Suggestion:
Update to version v2026.1.0https://github.com/discourse/discourse.git (GITHUB):
Affected version(s) =v2025.12.0-latest <v2025.12.0Fix Suggestion:
Update to version v2025.12.0Related Resources (1)
Do you need more information?
Contact UsCVSS v4
Base Score:
5.1
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
PASSIVE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
LOW
Vulnerable System Availability
LOW
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
4.6
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
LOW
Weakness Type (CWE)
Improper Encoding or Escaping of Output
EPSS
Base Score:
0.03
