JWT Token Exposure Affecting auth0-wcf-service-jwt package, versions [,1.0.4)

  • Attack Complexity


  • Confidentiality


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  • snyk-id


  • published

    1 Apr 2019

  • disclosed

    15 Feb 2019

  • credit

    Conny Dahlgren, Security Researcher at DevilSec AB

How to fix?

Upgrade Auth0-WCF-Service-JWT to version 1.0.4 or higher.


Auth0-WCF-Service-JWT is a ServiceAuthorizationManager from WCF that will extract the bearer JWT from Authorization header, validate it and then set the principal to a ClaimsPrincipal.

Affected versions of this package are vulnerable to JWT Token Exposure. The library leaked a token signature in an error message which would allow an attacker to forge an arbitrary JWT token.