{"id":"BIT-discourse-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":["CVE-2026-91123","GHSA-6pwj-wgg8-4rjc"],"modified":"2026-10-01T10:10:49.528015811Z","published":"2026-10-01T09:29:30.840Z","database_specific":{"cpes":["cpe:2.3:a:discourse:discourse:*:*:*:*:stable:*:*:*","cpe:2.3:a:discourse:discourse:*:*:*:*:beta:*:*:*"],"severity":"High"},"references":[{"type":"WEB","url":"https://github.com/discourse/discourse/commit/042d7b159beda4f74d23e245e8b2e396d9ff8318"},{"type":"WEB","url":"https://github.com/discourse/discourse/commit/097ce5600a2d74d9c68e57974597ab2684bd2a24"},{"type":"WEB","url":"https://github.com/discourse/discourse/commit/0b5a27e689925edce9ba9b14110022435d2b94be"},{"type":"WEB","url":"https://github.com/discourse/discourse/commit/142f5155ad8e56ddb8012c4e70c69a03dedc0579"},{"type":"WEB","url":"https://github.com/discourse/discourse/pull/42882"},{"type":"WEB","url":"https://github.com/discourse/discourse/security/advisories/GHSA-6pwj-wgg8-4rjc"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-91123"}],"affected":[{"package":{"name":"discourse","ecosystem":"Bitnami","purl":"pkg:bitnami/discourse"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2026.8.0"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/discourse/BIT-discourse-2026-91123.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N"}]}],"schema_version":"1.9.0"}