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nodejsAnonymousNODEJS:1766
HistoryJul 19, 2021 - 9:26 p.m.

Hostname spoofing via backslashes in URL

2021-07-1921:26:16
Anonymous
www.npmjs.com
51

0.001 Low

EPSS

Percentile

32.7%

Overview

Impact

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.

Patches

Version 1.19.7 is patched against all known payload variants.

Recommendation

Upgrade to version 1.19.7 or later

References

CPENameOperatorVersion
urijslt1.19.7

0.001 Low

EPSS

Percentile

32.7%