Gradient is a nix-based continuous integration system. In 1.1.0, when GRADIENT_DISCOVERABLE=true (the default, and the NixOS module default), anyone who can reach /proto can register as a worker without any credentials by sending a fresh, never-registered worker UUID. The resulting session has PeerAuth::Open, i.e. it sees jobs from every organisation, and can immediately NarPush/NarUploaded arbitrary store paths into nar_storage and the cached_path table. This vulnerability is fixed in 1.1.1.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:LI:HA:H9.4/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H