{"id":"CVE-2026-91123","summary":"Discourse: Reject literal backslash path separators in iframe src traversal guard","details":"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.","aliases":["GHSA-6pwj-wgg8-4rjc"],"modified":"2026-09-26T03:47:49.775457955Z","published":"2026-09-24T16:54:59.357Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-22"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91123.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91123.json"},{"type":"ADVISORY","url":"https://github.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-91123"},{"type":"FIX","url":"https://github.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318"},{"type":"FIX","url":"https://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24"},{"type":"FIX","url":"https://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be"},{"type":"FIX","url":"https://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579"},{"type":"FIX","url":"https://github.com/discourse/discourse/pull/42882"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/discourse/discourse","events":[{"introduced":"0"},{"introduced":"ded677e00beb0e9bae6e70b69582aecfb72b5477"},{"introduced":"06d03da34c4ed09ea59f917f045ba250d2b6320d"},{"introduced":"322d3c0ac6a8f133b3f82875e9dbbe310f638c1b"},{"fixed":"fb9247e04a826ab8e4d91168b3c4c839ec40bccc"},{"fixed":"3ab62a8397926ed934b667a5db06284c45b4c774"},{"fixed":"777cb880553b517bc9ae502e935a160332e48b78"},{"fixed":"e808d0853e013abf90e648e53ebd606c49ccb19f"},{"fixed":"042d7b159beda4f74d23e245e8b2e396d9ff8318"},{"fixed":"097ce5600a2d74d9c68e57974597ab2684bd2a24"},{"fixed":"0b5a27e689925edce9ba9b14110022435d2b94be"},{"fixed":"142f5155ad8e56ddb8012c4e70c69a03dedc0579"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"0"},{"fixed":"2026.8.0"},{"introduced":"2026.7.0-latest"},{"fixed":"2026.7.2"},{"introduced":"2026.6.0-latest"},{"fixed":"2026.6.3"},{"introduced":"2026.1.0-latest"},{"fixed":"2026.1.8"}]}}],"versions":["v2026.1.7","v2026.7.1","v2026.6.2","v2026.8.0-latest.1","v2026.1.6","v2026.7.0","v2026.6.1","v2026.8.0-latest","_gh-attach-assets","v2026.1.5","v2026.6.0","v2026.7.0-latest","v2026.6.0-latest","v2026.1.4","v2026.1.3","v2026.1.2","v2026.1.1","v2026.1.0","stable","esr","v2026.1.0-latest"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-91123.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N"}]}