CVE-2026-27166

low-risk
Published 2026-03-19

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.

Do I need to act?

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0.03% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
4
CVSS 4.1/10 Medium
NETWORK / LOW complexity

Affected Products (2)

Affected Vendors

Discourse

References (2)

Patch https://github.com/discourse/discourse/commit/c4762a4fac2f61f52f325396b11d3aeb95...
Vendor Advisory https://github.com/discourse/discourse/security/advisories/GHSA-h653-cq78-vjj2
25
/ 100
low-risk
Severity 18/34 · Moderate
Exploitability 0/34 · Minimal
Exposure 7/34 · Low