CVE-2025-66488: Discourse allows script execution in uploaded HTML/XML files on S3
Affected: discourse · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 9% of scored CVEs
DescriptionCVE.org
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 products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- discourse · discourse< 3.5.4; >= 2025.11.0-latest, < 2025.11.2; >= 2025.12.0-latest, < 2025.12.1; >= 2026.1.0-latest, < 2026.1.0
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- discourse
- Published
- January 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2025-66488 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.