{"id":"CVE-2026-91123","state":"PUBLISHED","title":"Discourse: Reject literal backslash path separators in iframe src traversal guard","description":"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.","publishedAt":"2026-09-24T16:54:59.357Z","updatedAt":"2026-09-24T17:11:34.752Z","severity":{"score":7.2,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["discourse discourse"],"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"}]}],"references":["https://github.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc","https://github.com/discourse/discourse/pull/42882","https://github.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318","https://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24","https://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be","https://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579"],"weaknesses":["CWE-22"],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/91xxx/CVE-2026-91123.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-91123","state":"PUBLISHED","datePublished":"2026-09-24T16:54:59.357Z","dateUpdated":"2026-09-24T17:11:34.752Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-09-14T19:36:48.843Z"},"containers":{"cna":{"title":"Discourse: Reject literal backslash path separators in iframe src traversal guard","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."}],"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"}]}],"references":[{"url":"https://github.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc","name":"https://github.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/discourse/discourse/pull/42882","name":"https://github.com/discourse/discourse/pull/42882","tags":["x_refsource_MISC"]},{"url":"https://github.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318","name":"https://github.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318","tags":["x_refsource_MISC"]},{"url":"https://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24","name":"https://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24","tags":["x_refsource_MISC"]},{"url":"https://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be","name":"https://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be","tags":["x_refsource_MISC"]},{"url":"https://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579","name":"https://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579","tags":["x_refsource_MISC"]}],"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"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-22","lang":"en","description":"CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-09-24T16:54:59.357Z"},"source":{"advisory":"GHSA-6pwj-wgg8-4rjc","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","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"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-24T17:11:34.752Z"}}]}}}