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CVE-2018-6559

Published: 18 October 2018

The Linux kernel, as used in Ubuntu 18.04 LTS and Ubuntu 18.10, allows local users to obtain names of files in which they would not normally be able to access via an overlayfs mount inside of a user namespace.

From the Ubuntu Security Team

Philipp Wendler discovered that the overlayfs implementation in the Linux kernel did not properly verify the directory contents permissions from within a unprivileged user namespace. A local attacker could use this to expose sensitive information (protected file names).

Notes

AuthorNote
tyhicks
This CVE is specific to Ubuntu since Ubuntu allows overlayfs mounts
inside of user namespaces
This flaw was previously discovered and fixed as part of
CVE-2015-1328. The fix for CVE-2015-1328 was incorrectly dropped from the
Ubuntu kernel during a merge with related changes in the upstream Linux
kernel. CVE-2018-6559 represents the portion of CVE-2015-1328 that was
incorrectly reintroduced into the Ubuntu kernel.

Priority

Low

Cvss 3 Severity Score

3.3

Score breakdown

Status

Package Release Status
linux
Launchpad, Ubuntu, Debian
upstream Not vulnerable
(Ubuntu specific)
trusty Not vulnerable
(3.11.0-12.19)
xenial Not vulnerable
(4.2.0-16.19)
bionic
Released (4.15.0-42.45)
cosmic
Released (4.18.0-12.13)
Patches:
Introduced by

local-2018-6559-break

Fixed by local-2015-1328-fix|local-2018-6559-fix
linux-lts-trusty
Launchpad, Ubuntu, Debian
upstream
Released (2.6.12~rc2)
trusty Does not exist

xenial Does not exist

bionic Does not exist

cosmic Does not exist

linux-goldfish
Launchpad, Ubuntu, Debian
upstream
Released (2.6.12~rc2)
trusty Does not exist
(trusty was ignored [abandoned])
xenial Ignored
(end of life)
bionic Does not exist

cosmic Does not exist

linux-grouper
Launchpad, Ubuntu, Debian
upstream
Released (2.6.12~rc2)
trusty Does not exist
(trusty was ignored [abandoned])
xenial Does not exist

bionic Does not exist

cosmic Does not exist

linux-maguro
Launchpad, Ubuntu, Debian
upstream
Released (2.6.12~rc2)
trusty Does not exist
(trusty was ignored [abandoned])
xenial Does not exist

bionic Does not exist

cosmic Does not exist

linux-mako
Launchpad, Ubuntu, Debian
upstream
Released (2.6.12~rc2)
trusty Does not exist
(trusty was ignored [abandoned])
xenial Ignored
(abandoned)
bionic Does not exist

cosmic Does not exist

linux-manta
Launchpad, Ubuntu, Debian
upstream
Released (2.6.12~rc2)
trusty Does not exist
(trusty was ignored [abandoned])
xenial Does not exist

bionic Does not exist

cosmic Does not exist

linux-flo
Launchpad, Ubuntu, Debian
upstream
Released (2.6.12~rc2)
bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [abandoned])
xenial Ignored
(abandoned)
linux-aws
Launchpad, Ubuntu, Debian
upstream
Released (2.6.12~rc2)
trusty Not vulnerable
(4.4.0-1002.2)
xenial Not vulnerable
(4.4.0-1001.10)
bionic
Released (4.15.0-1029.30)
cosmic
Released (4.18.0-1006.7)
linux-azure
Launchpad, Ubuntu, Debian
upstream
Released (2.6.12~rc2)
trusty
Released (4.15.0-1035.36~14.04.2)
xenial
Released (4.15.0-1035.36~16.04.1)
bionic
Released (4.15.0-1035.36)
cosmic
Released (4.18.0-1006.6)
linux-azure-edge
Launchpad, Ubuntu, Debian
upstream
Released (2.6.12~rc2)
trusty Does not exist

bionic
Released (4.15.0-1035.36)
cosmic Does not exist

xenial
Released (4.15.0-1035.36~16.04.1)
linux-gcp
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1025.26)
cosmic
Released (4.18.0-1004.5)
trusty Does not exist

upstream
Released (2.6.12~rc2)
xenial
Released (4.15.0-1025.26~16.04.1)
linux-euclid
Launchpad, Ubuntu, Debian
upstream
Released (2.6.12~rc2)
trusty Does not exist

xenial Ignored
(was needs-triage ESM criteria)
bionic Does not exist

cosmic Does not exist

linux-aws-hwe
Launchpad, Ubuntu, Debian
upstream
Released (2.6.12~rc2)
trusty Does not exist

xenial Not vulnerable
(4.15.0-1030.31~16.04.1)
bionic Does not exist

cosmic Does not exist

linux-gcp-edge
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(4.18.0-1004.5~18.04.1)
cosmic Does not exist

trusty Does not exist

upstream
Released (2.6.12~rc2)
xenial Does not exist

linux-gke
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

trusty Does not exist

upstream
Released (2.6.12~rc2)
xenial Ignored
(end of standard support)
linux-hwe
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(4.18.0-13.14~18.04.1)
cosmic Does not exist

trusty Does not exist

upstream
Released (2.6.12~rc2)
xenial
Released (4.15.0-42.45~16.04.1)
linux-hwe-edge
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(4.18.0-12.13~18.04.1)
cosmic Does not exist

trusty Does not exist

upstream
Released (2.6.12~rc2)
xenial
Released (4.15.0-42.45~16.04.1)
linux-kvm
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1027.27)
cosmic
Released (4.18.0-1005.5)
trusty Does not exist

upstream
Released (2.6.12~rc2)
xenial Not vulnerable
(4.4.0-1004.9)
linux-lts-utopic
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [end of standard support])
upstream
Released (2.6.12~rc2)
xenial Does not exist

linux-lts-vivid
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [end of standard support])
upstream
Released (2.6.12~rc2)
xenial Does not exist

linux-lts-wily
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

trusty Does not exist
(trusty was ignored [end of standard support])
upstream
Released (2.6.12~rc2)
xenial Does not exist

linux-lts-xenial
Launchpad, Ubuntu, Debian
bionic Does not exist

cosmic Does not exist

trusty Not vulnerable
(4.4.0-13.29~14.04.1)
upstream
Released (2.6.12~rc2)
xenial Does not exist

linux-oem
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1028.33)
cosmic
Released (4.15.0-1028.33)
trusty Does not exist

upstream
Released (2.6.12~rc2)
xenial Ignored
(end of standard support, was needs-triage)
linux-oracle
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(4.15.0-1007.9)
cosmic Not vulnerable

trusty Does not exist

upstream
Released (2.6.12~rc2)
xenial Not vulnerable
(4.15.0-1007.9~16.04.1)
linux-raspi2
Launchpad, Ubuntu, Debian
bionic
Released (4.15.0-1029.31)
cosmic
Released (4.18.0-1007.9)
trusty Does not exist

upstream
Released (2.6.12~rc2)
xenial Not vulnerable
(4.2.0-1013.19)
linux-snapdragon
Launchpad, Ubuntu, Debian
bionic Not vulnerable

cosmic Does not exist

trusty Does not exist

upstream
Released (2.6.12~rc2)
xenial Not vulnerable
(4.4.0-1012.12)

Severity score breakdown

Parameter Value
Base score 3.3
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality Low
Integrity impact None
Availability impact None
Vector CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N