jwx is a Go module implementing various JWx (JWA/JWE/JWK/JWS/JWT, otherwise known as JOSE) technologies. Calling jws.Parse with a JSON serialized payload where the signature field is present while protected is absent can lead to a nil pointer dereference. The vulnerability can be used to crash/DOS a system doing JWS verification. This vulnerability has been patched in versions 2.0.19 and 1.2.28.