1.5 JWT Best Current Practices

The minimum recommendations to defend your JWT against the threats mentioned previously are :

Perform Algorithm Verification

Enable the caller to specify a supported set of algorithms and do not use any other algorithms when performing cryptographic operations.
Ensure that the alg or enc header specifies the same algorithm that is used for the cryptographic operation.
Each key must be used exactly by one algorithm only.
Check the key each time the cryptographic operation is performed.

Consider the JWS as invalid if the algorithm is not accepted by the application, even if the JWS can be successfully validated.
Only allow the use of cryptographically current algorithms that meet the security requirements of the application.
Design your application to enable cryptographic agility.
Do not generate or consume tokens using none unless explicitly requested by the caller.
Avoid all RSA-PKCS1 v1.5 encryption algorithm and prefer RSAES-OAEP.
Use the deterministic approach if you want to implement ECDSA.

Reject any cryptographic operation use in JWT if any validation step has failed.
Validate both outer and inner operations in nested JWT by using the keys and algorithms supplied by the application.

Human-memorizable passwords MUST NOT be directly used as the key to a keyed-MAC algorithm such as "HS256".

Do not use or allow the use of other Unicode encodings for encoding and decoding JSON used in Header Parameters and JWT Claims.

Reject the JWT if it does not contain the iss (issuer) claim.
Validate the cryptographic keys used for the cryptographic operations in the JWT belong to the issuer.
Validate that the sub (subject) value corresponds to a valid subject and/or issuer-subject pair at the application. Reject the JWT if the issuer, subject, or the pair are invalid.

JWT must contain an aud (audience) claim that can be used to determine whether the JWT is being used by an intended party or was substituted by an attacker at an unintended party.
Validate the audience value and reject the JWT if the audience value is not present or not associated with the recipient.