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.
Upgrade to version 1.19.7 or later