CVE-2017-15131
Publication date 9 January 2018
Last updated 26 August 2025
Ubuntu priority
Description
It was found that system umask policy is not being honored when creating XDG user directories, since Xsession sources xdg-user-dirs.sh before setting umask policy. This only affects xdg-user-dirs before 0.15.5 as shipped with Red Hat Enterprise Linux.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| xdg-user-dirs | 25.10 questing |
Not affected
|
| 25.04 plucky |
Not affected
|
|
| 24.04 LTS noble |
Not affected
|
|
| 22.04 LTS jammy |
Needs evaluation
|
|
| 20.04 LTS focal |
Not affected
|
|
| 18.04 LTS bionic |
Not affected
|
|
| 16.04 LTS xenial |
Not affected
|
|
| 14.04 LTS trusty | Not in release |
Notes
seth-arnold
This feels like a fundamental misunderstanding of Unix model to assume that every task run on behalf of a user will be started as a child process of bash or sh run as an interactive or login shell. Environments that want a specific umask set for users should use the pam_umask(8) module as part of the login process. Environments that need a specific umask set for compliance reasons should investigate the feasibility of preparing a single-purpose LSM or seccomp jail interface of some sort.
rodrigo-zaiden
pam_umask is being used to set umask when an interactive session is started, so Ubuntu is not affected by this CVE.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score |
7.8 · High
|
| Attack vector | Local |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | High |
| Integrity impact | High |
| Availability impact | High |
| Vector | CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |