{"schema_version":"1.7.3","id":"GHSA-whrj-4476-wvmp","published":"2026-02-17T18:46:35Z","modified":"2026-03-10T18:46:35.394964Z","aliases":["CVE-2026-25500"],"related":["CGA-c5jr-5288-fhr3"],"summary":"Stored XSS in Rack::Directory via javascript: filenames rendered into anchor href","details":"## Summary\n\n`Rack::Directory` generates an HTML directory index where each file entry is rendered as a clickable link. If a file exists on disk whose basename begins with the `javascript:` scheme (e.g. `javascript:alert(1)`), the generated index includes an anchor whose `href` attribute is exactly `javascript:alert(1)`. Clicking this entry executes arbitrary JavaScript in the context of the hosting application.\n\nThis results in a client-side XSS condition in directory listings generated by `Rack::Directory`.\n\n## Details\n\n`Rack::Directory` renders directory entries using an HTML row template similar to:\n\n```html\n<a href='%s'>%s</a>\n```\n\nThe `%s` placeholder is populated directly with the file’s basename. If the basename begins with `javascript:`, the resulting HTML contains an executable JavaScript URL:\n\n```html\n<a href='javascript:alert(1)'>javascript:alert(1)</a>\n```\n\nBecause the value is inserted directly into the `href` attribute without scheme validation or normalization, browsers interpret it as a JavaScript URI. When a user clicks the link, the JavaScript executes in the origin of the Rack application.\n\n## Impact\n\nIf `Rack::Directory` is used to expose filesystem contents over HTTP, an attacker who can create or upload files within that directory may introduce a malicious filename beginning with `javascript:`.\n\nWhen a user visits the directory listing and clicks the entry, arbitrary JavaScript executes in the application's origin. Exploitation requires user interaction (clicking the malicious entry).\n\n## Mitigation\n\n* Update to a patched version of Rack in which `Rack::Directory` prefixes generated anchors with a relative path indicator (e.g. `./filename`).\n* Avoid exposing user-controlled directories via `Rack::Directory`.\n* Apply a strict Content Security Policy (CSP) to reduce impact of potential client-side execution issues.\n* Where feasible, restrict or sanitize uploaded filenames to disallow dangerous URI scheme prefixes.\n\nHackerOne profile:\nhttps://hackerone.com/thesmartshadow\n\nGitHub account owner:\nAli Firas (@thesmartshadow)","affected":[{"package":{"name":"rack","ecosystem":"RubyGems","purl":"pkg:gem/rack"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.2.22"}]}],"versions":["0.1.0","0.2.0","0.3.0","0.4.0","0.9.0","0.9.1","1.0.0","1.0.1","1.1.0","1.1.1","1.1.1.pre","1.1.2","1.1.3","1.1.4","1.1.5","1.1.6","1.2.0","1.2.1","1.2.2","1.2.3","1.2.4","1.2.5","1.2.6","1.2.7","1.2.8","1.3.0","1.3.0.beta","1.3.0.beta2","1.3.1","1.3.10","1.3.2","1.3.3","1.3.4","1.3.5","1.3.6","1.3.7","1.3.8","1.3.9","1.4.0","1.4.1","1.4.2","1.4.3","1.4.4","1.4.5","1.4.6","1.4.7","1.5.0","1.5.0.beta.1","1.5.0.beta.2","1.5.1","1.5.2","1.5.3","1.5.4","1.5.5","1.6.0","1.6.0.beta","1.6.0.beta2","1.6.1","1.6.10","1.6.11","1.6.12","1.6.13","1.6.2","1.6.3","1.6.4","1.6.5","1.6.6","1.6.7","1.6.8","1.6.9","2.0.0.alpha","2.0.0.rc1","2.0.1","2.0.2","2.0.3","2.0.4","2.0.5","2.0.6","2.0.7","2.0.8","2.0.9","2.0.9.1","2.0.9.2","2.0.9.3","2.0.9.4","2.1.0","2.1.1","2.1.2","2.1.3","2.1.4","2.1.4.1","2.1.4.2","2.1.4.3","2.1.4.4","2.2.0","2.2.1","2.2.10","2.2.11","2.2.12","2.2.13","2.2.14","2.2.15","2.2.16","2.2.17","2.2.18","2.2.19","2.2.2","2.2.20","2.2.21","2.2.3","2.2.3.1","2.2.4","2.2.5","2.2.6","2.2.6.1","2.2.6.2","2.2.6.3","2.2.6.4","2.2.7","2.2.8","2.2.8.1","2.2.9"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-whrj-4476-wvmp/GHSA-whrj-4476-wvmp.json"}},{"package":{"name":"rack","ecosystem":"RubyGems","purl":"pkg:gem/rack"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.0.beta1"},{"fixed":"3.1.20"}]}],"versions":["3.0.0","3.0.0.beta1","3.0.0.rc1","3.0.1","3.0.10","3.0.11","3.0.12","3.0.13","3.0.14","3.0.15","3.0.16","3.0.17","3.0.18","3.0.2","3.0.3","3.0.4","3.0.4.1","3.0.4.2","3.0.5","3.0.6","3.0.6.1","3.0.7","3.0.8","3.0.9","3.0.9.1","3.1.0","3.1.1","3.1.10","3.1.11","3.1.12","3.1.13","3.1.14","3.1.15","3.1.16","3.1.17","3.1.18","3.1.19","3.1.2","3.1.3","3.1.4","3.1.5","3.1.6","3.1.7","3.1.8","3.1.9"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-whrj-4476-wvmp/GHSA-whrj-4476-wvmp.json"}},{"package":{"name":"rack","ecosystem":"RubyGems","purl":"pkg:gem/rack"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.2.0"},{"fixed":"3.2.5"}]}],"versions":["3.2.0","3.2.1","3.2.2","3.2.3","3.2.4"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-whrj-4476-wvmp/GHSA-whrj-4476-wvmp.json"}}],"references":[{"type":"WEB","url":"https://github.com/rack/rack/security/advisories/GHSA-whrj-4476-wvmp"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-25500"},{"type":"WEB","url":"https://github.com/rack/rack/commit/f2f225f297b99fbee3d9f51255d41f601fc40aff"},{"type":"PACKAGE","url":"https://github.com/rack/rack"},{"type":"WEB","url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rack/CVE-2026-25500.yml"}],"database_specific":{"cwe_ids":["CWE-79"],"github_reviewed":true,"github_reviewed_at":"2026-02-17T18:46:35Z","nvd_published_at":"2026-02-18T20:18:36Z","severity":"MODERATE"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"}]}