Forgeable Public/Private Tokens Affecting jws package, versions <3.0.0



    Attack Complexity High
    Scope Changed
    Confidentiality High
    Integrity High

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  • Snyk ID npm:jws:20160726
  • published 26 Jul 2016
  • disclosed 26 Jul 2016
  • credit Brian Brennan and Tim McLean

How to fix?

Upgrade jws to version 3.0.0 or later.


jws is an implementation of JSON Web Signatures. Affected versions of this package are vulnerable to an Authentication Bypass attack, due to the "algorithm" not being enforced in jws.verify(). Attackers are given the opportunity to choose the algorithm sent to the server and generate signatures with arbitrary contents. The server expects an asymmetric key (RSA) but is sent a symmetric key (HMAC-SHA) with RSA's public key, so instead of going through a key validation process, the server will think the public key is actually an HMAC private key.