Information
The signatureAlgorithm is used to sign the JWT and can be configured to use different algorithms like HS256 (symmetric), RS256 (asymmetric).
The OpenID Connect server provider should use an asymmetric algorithm to sign JSON Web Tokens (JWT) for better security since different keys are used for signing and verifying the token.
Solution
Add the signatureAlgorithm attribute to the openidConnectProvider element and set it to a strong algorithm, such as RS256 in ${server.config.dir}/configDropins/overrides/*.xml.
<openidConnectProvider signatureAlgorithm="RS256" />
<openidConnectClient signatureAlgorithm="RS256" />