{"schema":"threatline.record/2","record":{"id":"CVE-2026-91134","aliases":["GHSA-54vw-chv3-wjpv"],"summary":"Discourse: Block post iframes whose encoded userinfo bypasses the allowed_iframes allowlist","details":"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.","categories":["Applications & CMS"],"product":"discourse","vendor":"discourse","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-91134","source_modified_at":"2026-09-29T02:56:30.376Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"discourse","vendor":"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"}],"defaultStatus":null}],"fixed_versions":[],"cvss":5.4,"severity":"Medium","kev":{"listed":false},"epss":{"probability":0.00216,"percentile":0.11396,"score_date":"2026-10-23"},"published_at":"2026-09-24T16:51:34.057Z","modified_at":"2026-09-29T02:56:30.376Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-91134","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-09-29T02:56:30.376Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-91134","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/discourse/discourse/security/advisories/GHSA-54vw-chv3-wjpv","tags":["x_refsource_CONFIRM"]},{"source":"CVE List","url":"https://github.com/discourse/discourse/pull/42882","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://github.com/discourse/discourse/commit/0a8015e6c7a5079981843721494d30c9a91f5415","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://github.com/discourse/discourse/commit/1304b0c04f87534053b0d574ae5a9b9ba13dd590","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://github.com/discourse/discourse/commit/bac7dd1201911851462483271b4567246fa1309d","tags":["x_refsource_MISC"]},{"source":"CVE List","url":"https://github.com/discourse/discourse/commit/fed3a58c48412ce7207b72a4629ddbc44482cd64","tags":["x_refsource_MISC"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"partial","assessed_at":"2026-09-29T02:56:20.350456Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-09-29T02:56:30.376Z","content_hash":"76dc84345e373b37cfe5f1eeab84e6d1b286099052926b8ac668e49cd43c3af9"}}