{"id":"CVE-2026-72721","aliases":["BIT-discourse-2026-72721","EUVD-2026-55657","GHSA-3x7x-24rq-h5j6"],"status":"published","title":"Discourse: Onebox Domain Blocklist Bypass via Case-Sensitive Comparison","description":"Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, Onebox::DomainChecker.is_blocked? compares hostnames and SiteSetting.blocked_onebox_domains entries case-sensitively, allowing an attacker to bypass configured Onebox domain restrictions by changing character casing in a redirect target hostname. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00585,"percentile":0.48464,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-178"],"published":"2026-08-10T15:48:30Z","modified":"2026-10-28T02:30:28Z","fixes":[{"ecosystem":"Bitnami","package":"discourse","fixed_in":["2026.1.6","2026.5.2","2026.6.1"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Bitnami","package":"discourse","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2026.1.6"},{"introduced":"2026.5.0"},{"fixed":"2026.5.2"},{"introduced":"2026.6.0"},{"fixed":"2026.6.1"}]}]}],"products":[{"vendor":"discourse","product":"discourse"}],"references":[{"url":"https://github.com/discourse/discourse/security/advisories/GHSA-3x7x-24rq-h5j6","tags":["x_refsource_CONFIRM","web","advisory"]},{"url":"https://github.com/discourse/discourse/pull/42091","tags":["x_refsource_MISC","web","fix"]},{"url":"https://github.com/discourse/discourse/pull/42092","tags":["x_refsource_MISC","web","fix"]},{"url":"https://github.com/discourse/discourse/pull/42093","tags":["x_refsource_MISC","web","fix"]},{"url":"https://github.com/discourse/discourse/pull/42094","tags":["x_refsource_MISC","web","fix"]},{"url":"https://github.com/discourse/discourse/commit/a3e10759fef47f03d450649bb51d9e84f4c68b8f","tags":["x_refsource_MISC","web","fix"]},{"url":"https://github.com/discourse/discourse/commit/c2eb6b0e5597d6f28f4be739b83300bc9c69e3cd","tags":["x_refsource_MISC","web","fix"]},{"url":"https://github.com/discourse/discourse/commit/caa615c371b1696982ee11ac8f3558f0f8ced584","tags":["x_refsource_MISC","web","fix"]},{"url":"https://github.com/discourse/discourse/commit/f503971d311b7b0dfdb751ee8cfd67e8cb99f5c5","tags":["x_refsource_MISC","web","fix"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72721","tags":["web","advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72721.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-72721","title":"Discourse: Onebox Domain Blocklist Bypass via Case-Sensitive Comparison","description":"Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, Onebox::DomainChecker.is_blocked? compares hostnames and SiteSetting.blocked_onebox_domains entries case-sensitively, allowing an attacker to bypass configured Onebox domain restrictions by changing character casing in a redirect target hostname. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.","status":"published","published":"2026-08-10T15:48:30.548Z","modified":"2026-08-10T16:59:07.554Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-178"],"updated_at":"2026-11-02T14:19:51.663093Z"}],"euvd":[{"id":"EUVD-2026-55657","description":"Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, Onebox::DomainChecker.is_blocked? compares hostnames and SiteSetting.blocked_onebox_domains entries case-sensitively, allowing an attacker to bypass configured Onebox domain restrictions by changing character casing in a redirect target hostname. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.","status":"published","published":"2026-08-10T15:48:30Z","modified":"2026-08-10T16:59:07Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"updated_at":"2026-11-02T18:02:01.941928Z"}],"nvd":[{"id":"CVE-2026-72721","description":"Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, Onebox::DomainChecker.is_blocked? compares hostnames and SiteSetting.blocked_onebox_domains entries case-sensitively, allowing an attacker to bypass configured Onebox domain restrictions by changing character casing in a redirect target hostname. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.","status":"published","published":"2026-08-10T16:19:49.36Z","modified":"2026-09-08T20:54:37.79Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-178"],"updated_at":"2026-11-02T14:12:36.102748Z"}],"osv":[{"id":"CVE-2026-72721","title":"Discourse: Onebox Domain Blocklist Bypass via Case-Sensitive Comparison","description":"Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, Onebox::DomainChecker.is_blocked? compares hostnames and SiteSetting.blocked_onebox_domains entries case-sensitively, allowing an attacker to bypass configured Onebox domain restrictions by changing character casing in a redirect target hostname. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.","status":"published","published":"2026-08-10T15:48:30.548Z","modified":"2026-10-28T02:30:28.063566884Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","level":"medium"}],"cwes":["CWE-178"],"updated_at":"2026-11-02T15:45:15.88521Z"},{"id":"BIT-discourse-2026-72721","title":"Discourse: Onebox Domain Blocklist Bypass via Case-Sensitive Comparison","description":"Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, Onebox::DomainChecker.is_blocked? compares hostnames and SiteSetting.blocked_onebox_domains entries case-sensitively, allowing an attacker to bypass configured Onebox domain restrictions by changing character casing in a redirect target hostname. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.","status":"published","published":"2026-08-17T05:44:20.901Z","modified":"2026-08-17T08:10:35.880164157Z","updated_at":"2026-11-02T15:28:29.152062Z"}]}}