Spring Framework, version 5.1, versions 5.0.x prior to 5.0.10, versions 4.3.x prior to 4.3.20, and older unsupported versions on the 4.2.x branch provide support for range requests when serving static resources through the ResourceHttpRequestHandler, or starting in 5.0 when an annotated controller returns an org.springframework.core.io.Resource. A malicious user (or attacker) can add a range header with a high number of ranges, or with wide ranges that overlap, or both, for a denial of service attack. This vulnerability affects applications that depend on either spring-webmvc or spring-webflux. Such applications must also have a registration for serving static resources (e.g. JS, CSS, images, and others), or have an annotated controller that returns an org.springframework.core.io.Resource. Spring Boot applications that depend on spring-boot-starter-web or spring-boot-starter-webflux are ready to serve static resources out of the box and are therefore vulnerable.

Spring Framework, versions 5.0.x prior to 5.0.7 and 4.3.x prior to 4.3.18 and older unsupported versions, allows web applications to enable cross-domain requests via JSONP (JSON with Padding) through AbstractJsonpResponseBodyAdvice for REST controllers and MappingJackson2JsonView for browser requests. Both are not enabled by default in Spring Framework nor Spring Boot, however, when MappingJackson2JsonView is configured in an application, JSONP support is automatically ready to use through the "jsonp" and "callback" JSONP parameters, enabling cross-domain requests.