{"id":"CVE-2026-27166","state":"PUBLISHED","title":"Discourse vulnerable to HTML injection via prohibited iframe URLs","description":"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.","publishedAt":"2026-03-19T20:29:22.570Z","updatedAt":"2026-03-21T03:31:58.296Z","severity":{"score":4.1,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["discourse discourse"],"affected":[{"vendor":"discourse","product":"discourse","versions":[{"version":"< 2026.3.0-latest.1","status":"affected"},{"version":">= 2026.2.0-latest, < 2026.2.1","status":"affected"},{"version":">= 2026.1.0-latest, < 2026.1.2","status":"affected"}]}],"references":["https://github.com/discourse/discourse/security/advisories/GHSA-h653-cq78-vjj2","https://github.com/discourse/discourse/commit/c4762a4fac2f61f52f325396b11d3aeb955ea925"],"weaknesses":["CWE-80"],"ingestedAt":"2026-10-29T20:11:31.369Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/27xxx/CVE-2026-27166.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-27166","state":"PUBLISHED","datePublished":"2026-03-19T20:29:22.570Z","dateUpdated":"2026-03-21T03:31:58.296Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-02-18T00:18:53.962Z"},"containers":{"cna":{"title":"Discourse vulnerable to HTML injection via prohibited iframe URLs","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"discourse","product":"discourse","versions":[{"version":"< 2026.3.0-latest.1","status":"affected"},{"version":">= 2026.2.0-latest, < 2026.2.1","status":"affected"},{"version":">= 2026.1.0-latest, < 2026.1.2","status":"affected"}]}],"references":[{"url":"https://github.com/discourse/discourse/security/advisories/GHSA-h653-cq78-vjj2","name":"https://github.com/discourse/discourse/security/advisories/GHSA-h653-cq78-vjj2","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/discourse/discourse/commit/c4762a4fac2f61f52f325396b11d3aeb955ea925","name":"https://github.com/discourse/discourse/commit/c4762a4fac2f61f52f325396b11d3aeb955ea925","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":4.1,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"LOW","privilegesRequired":"LOW","scope":"CHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-80","lang":"en","description":"CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-03-19T20:29:22.570Z"},"source":{"advisory":"GHSA-h653-cq78-vjj2","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-03-21T03:31:46.439342Z","id":"CVE-2026-27166","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-03-21T03:31:58.296Z"}}]}}}