CVE-2026-27166
Discourse vulnerable to HTML injection via prohibited iframe URLs
CVSS Score
4.1
EPSS Score
0.0%
EPSS Percentile
8th
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.
| CWE | CWE-80 |
| Vendor | discourse |
| Product | discourse |
| Published | Mar 19, 2026 |
| Last Updated | Mar 21, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None
Affected Versions
discourse / discourse
< 2026.3.0-latest.1 >= 2026.2.0-latest, < 2026.2.1 >= 2026.1.0-latest, < 2026.1.2