{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-91134","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-09-14T19:36:48.844Z","datePublished":"2026-09-24T16:51:34.057Z","dateUpdated":"2026-09-29T02:56:30.376Z"},"containers":{"cna":{"title":"Discourse: Block post iframes whose encoded userinfo bypasses the allowed_iframes allowlist","problemTypes":[{"descriptions":[{"cweId":"CWE-20","lang":"en","description":"CWE-20: Improper Input Validation","type":"CWE"}]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.4,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N","version":"3.1"}}],"references":[{"name":"https://github.com/discourse/discourse/security/advisories/GHSA-54vw-chv3-wjpv","tags":["x_refsource_CONFIRM"],"url":"https://github.com/discourse/discourse/security/advisories/GHSA-54vw-chv3-wjpv"},{"name":"https://github.com/discourse/discourse/pull/42882","tags":["x_refsource_MISC"],"url":"https://github.com/discourse/discourse/pull/42882"},{"name":"https://github.com/discourse/discourse/commit/0a8015e6c7a5079981843721494d30c9a91f5415","tags":["x_refsource_MISC"],"url":"https://github.com/discourse/discourse/commit/0a8015e6c7a5079981843721494d30c9a91f5415"},{"name":"https://github.com/discourse/discourse/commit/1304b0c04f87534053b0d574ae5a9b9ba13dd590","tags":["x_refsource_MISC"],"url":"https://github.com/discourse/discourse/commit/1304b0c04f87534053b0d574ae5a9b9ba13dd590"},{"name":"https://github.com/discourse/discourse/commit/bac7dd1201911851462483271b4567246fa1309d","tags":["x_refsource_MISC"],"url":"https://github.com/discourse/discourse/commit/bac7dd1201911851462483271b4567246fa1309d"},{"name":"https://github.com/discourse/discourse/commit/fed3a58c48412ce7207b72a4629ddbc44482cd64","tags":["x_refsource_MISC"],"url":"https://github.com/discourse/discourse/commit/fed3a58c48412ce7207b72a4629ddbc44482cd64"}],"affected":[{"vendor":"discourse","product":"discourse","versions":[{"version":"< 2026.8.0","status":"affected"},{"version":">= 2026.7.0-latest, < 2026.7.2","status":"affected"},{"version":">= 2026.6.0-latest, < 2026.6.3","status":"affected"},{"version":">= 2026.1.0-latest, < 2026.1.8","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-09-24T16:51:34.057Z"},"descriptions":[{"lang":"en","value":"Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the Discourse post sanitizer allowed a stored cross-origin iframe to bypass the allowed_iframes prefix policy when the iframe src contained encoded userinfo. The sanitizer validated a decoded form differently from the stored iframe src, allowing the browser to interpret an attacker-controlled host while the allowlist check accepted the encoded URL as an allowed prefix. An authenticated user with posting privileges could persist the iframe in a post and cause attacker-controlled cross-origin content to be rendered. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0."}],"source":{"advisory":"GHSA-54vw-chv3-wjpv","discovery":"UNKNOWN"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-29T02:56:20.350456Z","id":"CVE-2026-91134","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-09-29T02:56:30.376Z"}}]}}