{"id":"GHSA-46fp-8f5p-pf2m","summary":"Improper detection of disallowed URIs by Loofah `allowed_uri?`","details":"## Summary\n\n`Loofah::HTML5::Scrub.allowed_uri?` does not correctly reject `javascript:` URIs when the scheme is split by HTML entity-encoded control characters such as `
` (carriage return), `
` (line feed), or `	` (tab).\n\n## Details\n\nThe `allowed_uri?` method strips literal control characters before decoding HTML entities. Payloads like `java
script:alert(1)` survive the control character strip, then `
` is decoded to a carriage return, producing `java\\rscript:alert(1)`.\n\nNote that the Loofah sanitizer's default `sanitize()` path is **not affected** because Nokogiri decodes HTML entities during parsing before Loofah evaluates the URI protocol. This issue only affects direct callers of the `allowed_uri?` string-level helper when passing HTML-encoded strings.\n\n## Impact\n\nApplications that call `Loofah::HTML5::Scrub.allowed_uri?` to validate user-controlled URLs and then render approved URLs into `href` or other browser-interpreted URI attributes may be vulnerable to cross-site scripting (XSS).\n\nThis only affects Loofah `2.25.0`.\n\n## Mitigation\n\nUpgrade to Loofah \u003e= `2.25.1`.\n\n## Credit\n\nResponsibly reported by HackOne user `@smlee`.","modified":"2026-09-10T03:50:36.988646266Z","published":"2026-03-18T17:26:48Z","database_specific":{"nvd_published_at":null,"cwe_ids":["CWE-79"],"severity":"LOW","github_reviewed":true,"github_reviewed_at":"2026-03-18T17:26:48Z"},"references":[{"type":"WEB","url":"https://github.com/flavorjones/loofah/security/advisories/GHSA-46fp-8f5p-pf2m"},{"type":"PACKAGE","url":"https://github.com/flavorjones/loofah"}],"affected":[{"package":{"name":"loofah","ecosystem":"RubyGems","purl":"pkg:gem/loofah"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.25.0"},{"fixed":"2.25.1"}]}],"versions":["2.25.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-46fp-8f5p-pf2m/GHSA-46fp-8f5p-pf2m.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U"}]}