CVE-2020-26160

If a JWT contains an audience claim with an array of strings, rather than a single string, and MapClaims.VerifyAudience is called with req set to false, then audience verification will be bypassed, allowing an invalid set of audiences to be provided.

jwt-go allows attackers to bypass intended access restrictions in situations with `[]string{}` for `m["aud"]` (which is allowed by the specification). Because the type assertion fails, "" is the value of aud. This is a security problem if the JWT token is presented to a service that lacks its own audience check. There is no patch available and users of jwt-go are advised to migrate to [golang-jwt](https://github.com/golang-jwt/jwt) at version 3.2.1

jwt-go versiones anteriores a 4.0.0-preview1, permite a atacantes omitir las restricciones de acceso previstas en situaciones con []string{} para m["aud"] (que está permitido por la especificación). Porque la aserción de tipo presenta un fallo, "" es el valor de aud. Este es un problema de seguridad si el token JWT es presentado para un servicio que carece de su propia comprobación de audiencia