Discourse vulnerable to HTML injection via prohibited iframe… (CVE-2026-27166)

Summary

Discourse vulnerable to HTML injection via prohibited iframe URLs

Original description

The description as published by the source.

Discourse is an open source discussion platform. Prior to versions 2026.3.0, 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, 2026.2.1 and 2026.1.2. To workaround this issue, remove Codepen from the list of allowed iframes.

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

Affected packages

Bitnami discourse

[{"type":"SEMVER","events":[{"introduced":"2026.1.0"},{"fixed":"2026.1.2"},{"introduced":"2026.2.0"},{"fixed":"2026.2.1"},{"introduced":"2026.3.0"},{"fixed":"2026.3.0"}]}]

References

advisory github.com
patch github.com
web nvd.nist.gov