Ecosyste.ms: Advisories

Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTMzMjktcGp3di1manBn

Hostname spoofing via backslashes in URL

Impact

If using affected versions to determine a URL's hostname, the hostname can be spoofed by using a backslash (\) character followed by an at (@) character. 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\@observed-example.com
Escaped string: https://expected-example.com\\@observed-example.com (JavaScript strings must escape backslash)

Affected versions incorrectly return observed-example.com. 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 1.19.4 is patched against all known payload variants. Version 1.19.3 has a partial patch but is still vulnerable to a payload variant.

References

https://github.com/medialize/URI.js/releases/tag/v1.19.4 (complete fix for this bypass)
https://github.com/medialize/URI.js/releases/tag/v1.19.3 (partial fix for this bypass)
PR #233 (initial fix for backslash handling)

For more information

If you have any questions or comments about this advisory, open an issue in https://github.com/medialize/URI.js

Reporter credit

Alesandro Ortiz

Permalink: https://github.com/advisories/GHSA-3329-pjwv-fjpg
JSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTMzMjktcGp3di1manBn
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Moderate
Classification: General
Published: over 3 years ago
Updated: about 1 year ago

CVSS Score: 6.5
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Identifiers: GHSA-3329-pjwv-fjpg, CVE-2020-26291
References:

• https://github.com/medialize/URI.js/security/advisories/GHSA-3329-pjwv-fjpg
• https://github.com/medialize/URI.js/releases/tag/v1.19.4
• https://www.npmjs.com/package/urijs
• https://nvd.nist.gov/vuln/detail/CVE-2020-26291
• https://github.com/medialize/URI.js/commit/b02bf037c99ac9316b77ff8bfd840e90becf1155
• https://www.npmjs.com/advisories/1595
• https://github.com/advisories/GHSA-3329-pjwv-fjpg

Repository: https://github.com/medialize/URI.js
Blast Radius: 34.3

Affected Packages