CVE-2025-66488
MEDIUM severity · CVSS 4.6 · CWE-116
4.6CVSS MEDIUM
Summary
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.
Impact & exploitability
Attack vectorNetwork
Attack complexityLow
Privileges requiredLow
User interactionRequired
Confidentiality impactNone
Integrity impactLow
Availability impactLow
Exploit probability (EPSS)0%
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L
Affected products we track (1)
Recommendation
Apply the vendor fix in your normal patch cycle. Open any affected product above for its exact safe version.