CVE-2025-66488 (GCVE-0-2025-66488)

Vulnerability from cvelistv5 – Published: 2026-01-28 18:15 – Updated: 2026-01-28 19:29
VLAI?
Title
Discourse allows script execution in uploaded HTML/XML files on S3
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.
Severity ?
4.6 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L
CWE
  • CWE-116 - Improper Encoding or Escaping of Output
Assigner
References
Impacted products
Vendor Product Version
discourse discourse Affected: < 3.5.4
Affected: >= 2025.11.0-latest, < 2025.11.2
Affected: >= 2025.12.0-latest, < 2025.12.1
Affected: >= 2026.1.0-latest, < 2026.1.0
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Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.