CVE-2026-27166 (GCVE-0-2026-27166)

Vulnerability from cvelistv5 – Published: 2026-03-19 20:29 – Updated: 2026-03-21 03:31
VLAI?
Title
Discourse vulnerable to HTML injection via prohibited iframe URLs
Summary
Discourse is an open source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1 and 2026.1.2, insufficient cleanup in the default Codepen allowed iframes value allows an attacker to trick a user into changing the URL of the main page. This issue has been fixed in versions 2026.3.0-latest.1, 2026.2.1 and 2026.1.2. To workaround this issue, remove Codepen from the list of allowed iframes.
Severity ?
4.1 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N
CWE
  • CWE-80 - Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
Assigner
References
Impacted products
Vendor Product Version
discourse discourse Affected: < 2026.3.0-latest.1
Affected: >= 2026.2.0-latest, < 2026.2.1
Affected: >= 2026.1.0-latest, < 2026.1.2
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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.