If using affected versions to determine a URL's hostname, the hostname can be spoofed by using a combination of backslash (\
) and slash (/
) characters as part of the scheme delimiter, e.g. scheme:/\/\/\hostname
. If the hostname is used in security decisions, the decision may be incorrect.
Depending on library usage and attacker intent, impacts may include allow/block list bypasses, SSRF attacks, open redirects, or other undesired behavior.
Example URL: https:/\/\/\expected-example.com/path
Escaped string: https:/\\/\\/\\expected-example.com/path
(JavaScript strings must escape backslash)
Affected versions incorrectly return no hostname. Patched versions correctly return expected-example.com
. Patched versions match the behavior of other parsers which implement the WHATWG URL specification, including web browsers and Node's built-in URL class.
Version 1.19.7 is patched against all known payload variants.
https://github.com/medialize/URI.js/releases/tag/v1.19.7 (fix for this particular bypass) https://github.com/medialize/URI.js/releases/tag/v1.19.6 (fix for related bypass) https://github.com/medialize/URI.js/releases/tag/v1.19.4 (fix for related bypass) https://github.com/medialize/URI.js/releases/tag/v1.19.3 (fix for related bypass) PR #233 (initial fix for backslash handling)
If you have any questions or comments about this advisory, open an issue in https://github.com/medialize/URI.js
ready-research via https://huntr.dev/
{ "nvd_published_at": "2021-07-16T11:15:00Z", "severity": "MODERATE", "github_reviewed_at": "2021-07-19T16:38:54Z", "github_reviewed": true, "cwe_ids": [ "CWE-601" ] }