It was discovered that snapctl user-open allowed altering the $XDG_DATA_DIRS environment variable when calling the system xdg-open. OpenURL() in usersession/userd/launcher.go would alter $XDG_DATA_DIRS to append a path to a directory controlled by the calling snap. A malicious snap could exploit this to bypass intended access restrictions to control how the host system xdg-open script opens the URL and, for example, execute a script shipped with the snap without confinement. This issue did not affect Ubuntu Core systems. Fixed in snapd versions 2.45.1ubuntu0.2, 2.45.1+18.04.2 and 2.45.1+20.04.2.
The product exposes a resource to the wrong control sphere, providing unintended actors with inappropriate access to the resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Ubuntu_linux | Canonical | 16.04 (including) | 16.04 (including) |
| Ubuntu_linux | Canonical | 18.04 (including) | 18.04 (including) |
| Ubuntu_linux | Canonical | 19.10 (including) | 19.10 (including) |
| Ubuntu_linux | Canonical | 20.04 (including) | 20.04 (including) |
| Snapd | Ubuntu | bionic | * |
| Snapd | Ubuntu | devel | * |
| Snapd | Ubuntu | eoan | * |
| Snapd | Ubuntu | focal | * |
| Snapd | Ubuntu | trusty | * |
| Snapd | Ubuntu | upstream | * |
| Snapd | Ubuntu | xenial | * |
Resources such as files and directories may be inadvertently exposed through mechanisms such as insecure permissions, or when a program accidentally operates on the wrong object. For example, a program may intend that private files can only be provided to a specific user. This effectively defines a control sphere that is intended to prevent attackers from accessing these private files. If the file permissions are insecure, then parties other than the user will be able to access those files. A separate control sphere might effectively require that the user can only access the private files, but not any other files on the system. If the program does not ensure that the user is only requesting private files, then the user might be able to access other files on the system. In either case, the end result is that a resource has been exposed to the wrong party.