{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-91123", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-09-14T19:36:48.843Z", "datePublished": "2026-09-24T16:54:59.357Z", "dateUpdated": "2026-09-24T17:11:34.752Z"}, "containers": {"cna": {"title": "Discourse: Reject literal backslash path separators in iframe src traversal guard", "problemTypes": [{"descriptions": [{"cweId": "CWE-22", "lang": "en", "description": "CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 7.2, "baseSeverity": "HIGH", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc"}, {"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/042d7b159beda4f74d23e245e8b2e396d9ff8318", "tags": ["x_refsource_MISC"], "url": "https://github.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318"}, {"name": "https://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24", "tags": ["x_refsource_MISC"], "url": "https://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24"}, {"name": "https://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be", "tags": ["x_refsource_MISC"], "url": "https://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be"}, {"name": "https://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579", "tags": ["x_refsource_MISC"], "url": "https://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579"}], "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": "2026-09-24T16:54:59.357Z"}, "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 iframe src traversal guard did not treat literal backslashes as path separators after decoded dot segments. A crafted source could therefore pass an allowed_iframes subpath check while browser URL normalization moved the iframe outside the intended allowed path. The resulting iframe could load content from a location that the administrator did not allow. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0."}], "source": {"advisory": "GHSA-6pwj-wgg8-4rjc", "discovery": "UNKNOWN"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-09-24T17:11:25.606443Z", "id": "CVE-2026-91123", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"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": "2026-09-24T17:11:34.752Z"}}]}}

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{"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 iframe src traversal guard did not treat literal backslashes as path separators after decoded dot segments. A crafted source could therefore pass an allowed_iframes subpath check while browser URL normalization moved the iframe outside the intended allowed path. The resulting iframe could load content from a location that the administrator did not allow. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0."}], "id": "CVE-2026-91123", "lastModified": "2026-09-24T17:17:08.690", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 7.2, "baseSeverity": "HIGH", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 2.7, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-09-24T17:17:08.560", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318"}, {"source": "security-advisories@github.com", "url": "https://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24"}, {"source": "security-advisories@github.com", "url": "https://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be"}, {"source": "security-advisories@github.com", "url": "https://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579"}, {"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-6pwj-wgg8-4rjc"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-22"}], "source": "security-advisories@github.com", "type": "Primary"}]}

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