{"id":"CVE-2026-27166","summary":"Discourse vulnerable to HTML injection via prohibited iframe URLs","details":"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.","aliases":["BIT-discourse-2026-27166","GHSA-h653-cq78-vjj2"],"modified":"2026-08-12T03:51:28.911865846Z","published":"2026-03-19T20:29:22.570Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-80"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27166.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/27xxx/CVE-2026-27166.json"},{"type":"ADVISORY","url":"https://github.com/discourse/discourse/security/advisories/GHSA-h653-cq78-vjj2"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27166"},{"type":"FIX","url":"https://github.com/discourse/discourse/commit/c4762a4fac2f61f52f325396b11d3aeb955ea925"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/discourse/discourse","events":[{"introduced":"0"},{"fixed":"896e810e1b296478bba91559a8fc89a9926f11fe"},{"introduced":"322d3c0ac6a8f133b3f82875e9dbbe310f638c1b"},{"fixed":"808b2ac23d8ff421563b40203091026732471c60"},{"introduced":"f7cec86997edc21d6074ceb7666f7e2e6e1b1fdf"},{"fixed":"f38464e46df1b8c51f7d60826502476908d6bb2b"},{"introduced":"896e810e1b296478bba91559a8fc89a9926f11fe"},{"fixed":"c4762a4fac2f61f52f325396b11d3aeb955ea925"}],"database_specific":{"cpe":["cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*","cpe:2.3:a:discourse:discourse:2026.3.0:*:*:*:latest:*:*:*"],"extracted_events":[{"introduced":"0"},{"fixed":"2026.3.0"},{"introduced":"2026.1.0"},{"fixed":"2026.1.2"},{"introduced":"2026.2.0"},{"fixed":"2026.2.1"},{"introduced":"2026.3.0"},{"last_affected":"2026.3.0"}],"source":["CPE_RANGE","CPE_STRING","REFERENCES"]}}],"versions":["2026.3.0","v2026.1.1","v2026.2.0","v2026.3.0-latest","v2026.1.0","stable","esr","v2026.2.0-latest","v2026.1.0-latest"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-27166.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N"}]}