JwtDecoders from issuer uri produces ClassCastException

[tiborkoch]

Describe the bug
Using the latest Spring Boot snapshot version (2.5.0-SNAPSHOT) that has Spring Security 5.5.0-RC1 as dependency, a ClassCastException is thrown when creating a JwtDecoder from an issuer uri.

Caused by: java.lang.ClassCastException: class com.nimbusds.jose.Algorithm cannot be cast to class com.nimbusds.jose.JWSAlgorithm (com.nimbusds.jose.Algorithm and com.nimbusds.jose.JWSAlgorithm are in unnamed module of loader 'app')
	at org.springframework.security.oauth2.jwt.JwtDecoderProviderConfigurationUtils.getSignatureAlgorithms(JwtDecoderProviderConfigurationUtils.java:93) ~[spring-security-oauth2-jose-5.5.0-RC1.jar:5.5.0-RC1]

It can be fixed by using

JWSAlgorithm jwsAlgorithm = JWSAlgorithm.parse(jwk.getAlgorithm().getName());
jwsAlgorithms.add(jwsAlgorithm);

instead of casting.

To Reproduce
Start the app in the provided repository.

Expected behavior
No errors on startup.

Sample
https://github.com/tiborkoch/spring-security-oauth2resourceserver

[ubaid4j]

I was testing latest Spring Boot snapshot version (2.5.0-SNAPSHOT) and I got the same above issue. Folllowing is the stacktrace:
Spring Boot Version: 2.5.0-SNAPSHOT
Spring Security Version: 5.5.0-RC1

Caused by: java.lang.ClassCastException: class com.nimbusds.jose.Algorithm cannot be cast to class com.nimbusds.jose.JWSAlgorithm (com.nimbusds.jose.Algorithm and com.nimbusds.jose.JWSAlgorithm are in unnamed module of loader 'app')
	at org.springframework.security.oauth2.jwt.JwtDecoderProviderConfigurationUtils.getSignatureAlgorithms(JwtDecoderProviderConfigurationUtils.java:93) ~[spring-security-oauth2-jose-5.5.0-RC1.jar:5.5.0-RC1]
	at org.springframework.security.oauth2.jwt.JwtDecoders.withProviderConfiguration(JwtDecoders.java:122) ~[spring-security-oauth2-jose-5.5.0-RC1.jar:5.5.0-RC1]
	at org.springframework.security.oauth2.jwt.JwtDecoders.fromIssuerLocation(JwtDecoders.java:102) ~[spring-security-oauth2-jose-5.5.0-RC1.jar:5.5.0-RC1]
	at com.ubaid.ms.countryservice.config.SecurityConfig.jwtDecoder(SecurityConfig.java:41) ~[classes/:na]
	at com.ubaid.ms.countryservice.config.SecurityConfig$$EnhancerBySpringCGLIB$$7ab3f55b.CGLIB$jwtDecoder$0(<generated>) ~[classes/:na]
	at com.ubaid.ms.countryservice.config.SecurityConfig$$EnhancerBySpringCGLIB$$7ab3f55b$$FastClassBySpringCGLIB$$70b6db75.invoke(<generated>) ~[classes/:na]
	at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) ~[spring-core-5.3.6.jar:5.3.6]
	at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:331) ~[spring-context-5.3.6.jar:5.3.6]
	at com.ubaid.ms.countryservice.config.SecurityConfig$$EnhancerBySpringCGLIB$$7ab3f55b.jwtDecoder(<generated>) ~[classes/:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.3.6.jar:5.3.6]
	... 61 common frames omitted

[jgrandja]

Thanks for the report @tiborkoch. I was able to reproduce the same issue with the provided sample.

The fix you suggested is correct. Would you be interested in submitting a PR for this fix?

[wsaca]

@tiborkoch I didnt have enough time to fix this issue, but if you can do it I share with you the old issue.

[tiborkoch]

@jgrandja @wsaca I'll do it, will try to submit the pr in a few days

[tiborkoch]

Fixed in #9658

[RobertHeim]

Is there a workaround until the fix is released?

[jzheaux]

Hi, @RobertHeim, yes, you can create the NimbusJwtDecoder instance directly, like so:

@Bean 
JwtDecoder jwtDecoder() {
    String issuerUri = ...;
    String jwkSetUri = ...;
    OAuth2TokenValidator<Jwt> validator = JwtValidators.createDefaultWithIssuer(issuerUri);
    NimbusJwtDecoder jwtDecoder = NimbusJwtDecoder.withJwtSetUri(jwkSetUri).build();
    jwtDecoder.setJwtValidator(validator);
    return jwtDecoder;
}

[jzheaux]

Or, if you are a Spring Boot application, then you can instead do:

spring:
  security:
    oauth2:
      resourceserver:
        jwt:
          issuer-uri: https://auth.example.org/issuer
          jwk-set-uri: https://auth.example.org/jwks

[RobertHeim]

Thanks for the fast feedback. That works!