{"id":"CVE-2026-126209","summary":"Loofah allowed_uri? treats javascript&#x3a alert(1) as safe","details":"Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. From 2.25.0 until 2.25.3, Loofah::HTML5::Scrub.allowed_uri? strips whitespace and control characters before decoding a semicolon-less numeric character reference, changing where the reference ends and hiding a javascript: or vbscript: scheme that a browser reconstructs. The bypass applies to encoded colons and encoded scheme letters when a stripped character terminates the numeric reference. An application that renders the approved value in href or another browser-interpreted URI attribute can allow cross-site scripting, and Rails::HTML::Sanitizer.allowed_uri? re-exports the affected helper. Loofah's default sanitize() path is not affected because Nokogiri decodes entities before URI evaluation. This issue is fixed in version 2.25.3.","aliases":["GHSA-p9wj-w8xq-vjx6"],"modified":"2026-11-13T10:46:14.312855734Z","published":"2026-11-12T21:01:58.128Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-184","CWE-79"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126209.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/126xxx/CVE-2026-126209.json"},{"type":"FIX","url":"https://github.com/flavorjones/loofah/commit/62c04841e8252a1b5373afcd2b89fb9b8279e317"},{"type":"FIX","url":"https://github.com/flavorjones/loofah/pull/324"},{"type":"WEB","url":"https://github.com/flavorjones/loofah/releases/tag/v2.25.3"},{"type":"ADVISORY","url":"https://github.com/flavorjones/loofah/security/advisories/GHSA-p9wj-w8xq-vjx6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-126209"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/flavorjones/loofah","events":[{"introduced":"e65bdddfd3381f3a131be7e137d89bb3959c072b"},{"fixed":"bbe007e52e8aeaa520b3e515235d467f5b1416e6"},{"fixed":"62c04841e8252a1b5373afcd2b89fb9b8279e317"}],"database_specific":{"extracted_events":[{"strategy":"StringRangeExpression","range":[{"introduced":"2.25.0"},{"fixed":"2.25.3"}],"source":"AFFECTED_FIELD"},{"range":[{"fixed":"62c04841e8252a1b5373afcd2b89fb9b8279e317"}],"source":"REFERENCES_COMMIT"},{"original_tag":"v2.25.3","range":[{"fixed":"bbe007e52e8aeaa520b3e515235d467f5b1416e6"}],"source":"REFERENCES_TAG"}]}}],"versions":["v2.25.2","v2.25.1","v2.25.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-126209.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"}]}