Nexus Repository 3 - Incorrect Authorization on Blobstore Group Endpoints

A vulnerability was identified in Sonatype Nexus Repository 3 in which two blobstore group management REST API endpoints did not correctly enforce the intended authorization check. A user granted only the nexus:blobstores:create permission could invoke these endpoints to convert an existing blobstore into a group blobstore, an action that should require the nexus:blobstores:update permission instead. This could result in unauthorized modification of blobstore configuration without administrator approval. The nexus:blobstores:create permission is a named permission that must be explicitly granted by an administrator; it is not held by default.