An issue was discovered in SDDM through 0.17.0. If configured with ReuseSession=true, the password is not checked for users with an already existing session. Any user with access to the system D-Bus can therefore unlock any graphical session. This is related to daemon/Display.cpp and helper/backend/PamBackend.cpp.
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Sddm | Sddm_project | * | 0.17.0 (including) |
| Sddm | Ubuntu | artful | * |
| Sddm | Ubuntu | bionic | * |
| Sddm | Ubuntu | cosmic | * |
| Sddm | Ubuntu | xenial | * |