CVE-2026-27166
MEDIUM severity · CVSS 4.1 · CWE-80
4.1CVSS MEDIUM
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.
Impact & exploitability
Attack vectorNetwork
Attack complexityLow
Privileges requiredLow
User interactionRequired
Confidentiality impactNone
Integrity impactLow
Availability impactNone
Exploit probability (EPSS)0%
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N
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.
Official patch: https://github.com/discourse/discourse/commit/c4762a4fac2f61f52f325396b11d3aeb955ea925 ↗