{"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": "2026-09-24T16:51:34.057Z"}, "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"}}}}

{}

{"affected": [{"affectedData": [{"product": "discourse", "vendor": "discourse", "versions": [{"status": "affected", "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"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "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."}], "id": "CVE-2026-91134", "lastModified": "2026-09-24T17:17:09.220", "metrics": {"cvssMetricV31": [{"cvssData": {"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"}, "exploitabilityScore": 2.8, "impactScore": 2.5, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-09-24T17:17:09.080", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/discourse/discourse/commit/0a8015e6c7a5079981843721494d30c9a91f5415"}, {"source": "security-advisories@github.com", "url": "https://github.com/discourse/discourse/commit/1304b0c04f87534053b0d574ae5a9b9ba13dd590"}, {"source": "security-advisories@github.com", "url": "https://github.com/discourse/discourse/commit/bac7dd1201911851462483271b4567246fa1309d"}, {"source": "security-advisories@github.com", "url": "https://github.com/discourse/discourse/commit/fed3a58c48412ce7207b72a4629ddbc44482cd64"}, {"source": "security-advisories@github.com", "url": "https://github.com/discourse/discourse/pull/42882"}, {"source": "security-advisories@github.com", "url": "https://github.com/discourse/discourse/security/advisories/GHSA-54vw-chv3-wjpv"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-20"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{}