Spring Cloud SSO Connector, version 2.1.2, contains a regression which disables issuer validation in resource servers that are not bound to the SSO service. In PCF deployments with multiple SSO service plans, a remote attacker can authenticate to unbound resource servers which use this version of the SSO Connector with tokens generated from another service plan.

Mitigation

Users of affected versions should apply the following mitigation:

• Releases that have fixed this issue include:
  • Spring Cloud SSO Connector: 2.1.3
• Alternatively, you can perform one of the following workarounds:
  • Bind your resource server to the SSO service plan via a service instance binding
  • Set “sso.connector.cloud.available=true” within your Spring application properties

References

• https://nvd.nist.gov/vuln/detail/CVE-2018-1256
• https://pivotal.io/security/cve-2018-1256
• pivotal-cf/spring-cloud-sso-connector@ef647a2