Spring Security versions 5.5.x prior to 5.5.1, 5.4.x prior to 5.4.7, 5.3.x prior to 5.3.10 and 5.2.x prior to 5.2.11 are susceptible to a Denial-of-Service (DoS) attack via the initiation of the Authorization Request in an OAuth 2.0 Client Web and WebFlux application. A malicious user or attacker can send multiple requests initiating the Authorization Request for the Authorization Code Grant, which has the potential of exhausting system resources using a single session or multiple sessions. This vulnerability exposes OAuth 2.0 Client applications that use HttpSessionOAuth2AuthorizationRequestRepository (Servlet) and WebSessionOAuth2ServerAuthorizationRequestRepository (Reactive).

• Spring Security
  • 5.5.x prior to 5.5.1
  • 5.4.x prior to 5.4.7
  • 5.3.x prior to 5.3.10
  • 5.2.x prior to 5.2.11

Users of affected versions should upgrade to the following versions:

• Spring Security
  • 5.5.1
  • 5.4.7
  • 5.3.10
  • 5.2.11

This issue was identified and responsibly reported by Craig Andrews (github.com/candrews).