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CVE-2018-6556

The lxc-user-nic component of LXC allows unprivileged users to open arbitrary files

3.3 LowFix available

lxc-user-nic when asked to delete a network interface will unconditionally open a user provided path. This code path may be used by an unprivileged user to check for the existence of a path which they wouldn't otherwise be able to reach. It may also be used to trigger side effects by causing a (read-only) open of special kernel files (ptmx, proc, sys). Affected releases are LXC: 2.0 versions above and including 2.0.9; 3.0 versions above and including 3.0.0, prior to 3.0.2.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
None
Availability
None

Exploit likelihood

0.35%Down 1.5 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 3.3

lxc-user-nic when asked to delete a network interface will unconditionally open a user provided path. This code path may be used by an unprivileged user to check for the existence of a path which they wouldn't otherwise be able to reach. It may also be used to trigger side effects by causing a (read-only) open of special kernel files (ptmx, proc, sys). Affected releases are LXC: 2.0 versions above and including 2.0.9; 3.0 versions above and including 3.0.0, prior to 3.0.2.

Record
CVE-2018-6556
CVSS 3.0
3.3 LowCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
CVSS 2.0
2.1 LowAV:L/AC:L/Au:N/C:P/I:N/A:N
Weakness
CWE-417
Updated
2026-11-02
CVE List No score

The lxc-user-nic component of LXC allows unprivileged users to open arbitrary files

lxc-user-nic when asked to delete a network interface will unconditionally open a user provided path. This code path may be used by an unprivileged user to check for the existence of a path which they wouldn't otherwise be able to reach. It may also be used to trigger side effects by causing a (read-only) open of special kernel files (ptmx, proc, sys). Affected releases are LXC: 2.0 versions above and including 2.0.9; 3.0 versions above and including 3.0.0, prior to 3.0.2.

Record
CVE-2018-6556
Updated
2026-11-02
EUVDEUVD-2018-18308 No score

lxc-user-nic when asked to delete a network interface will unconditionally open a user provided path. This code path may be used by an unprivileged user to check for the existence of a path which they wouldn't otherwise be able to reach. It may also be used to trigger side effects by causing a (read-only) open of special kernel files (ptmx, proc, sys). Affected releases are LXC: 2.0 versions above and including 2.0.9; 3.0 versions above and including 3.0.0, prior to 3.0.2.

Record
EUVD-2018-18308
Updated
2026-11-03
GitHub AdvisoriesGHSA-xg68-6jxg-5w7p 3.3

lxc-user-nic when asked to delete a network interface will unconditionally open a user provided...

lxc-user-nic when asked to delete a network interface will unconditionally open a user provided path. This code path may be used by an unprivileged user to check for the existence of a path which they wouldn't otherwise be able to reach. It may also be used to trigger side effects by causing a (read-only) open of special kernel files (ptmx, proc, sys). Affected releases are LXC: 2.0 versions above and including 2.0.9; 3.0 versions above and including 3.0.0, prior to 3.0.2.

Record
GHSA-xg68-6jxg-5w7p
CVSS 3.0
3.3 LowCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
OSVALPINE-CVE-2018-6556 3.3

lxc-user-nic when asked to delete a network interface will unconditionally open a user provided path. This code path may be used by an unprivileged user to check for the existence of a path which they wouldn't otherwise be able to reach. It may also be used to trigger side effects by causing a (read-only) open of special kernel files (ptmx, proc, sys). Affected releases are LXC: 2.0 versions above and including 2.0.9; 3.0 versions above and including 3.0.0, prior to 3.0.2.

Record
ALPINE-CVE-2018-6556
CVSS 3.0
3.3 LowCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
OSV 3.3

lxc-user-nic when asked to delete a network interface will unconditionally open a user provided path. This code path may be used by an unprivileged user to check for the existence of a path which they wouldn't otherwise be able to reach. It may also be used to trigger side effects by causing a (read-only) open of special kernel files (ptmx, proc, sys). Affected releases are LXC: 2.0 versions above and including 2.0.9; 3.0 versions above and including 3.0.0, prior to 3.0.2.

Record
CVE-2018-6556
CVSS 3.0
3.3 LowCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
Show 7 moreShow less
OSVDEBIAN-CVE-2018-6556 3.3

lxc-user-nic when asked to delete a network interface will unconditionally open a user provided path. This code path may be used by an unprivileged user to check for the existence of a path which they wouldn't otherwise be able to reach. It may also be used to trigger side effects by causing a (read-only) open of special kernel files (ptmx, proc, sys). Affected releases are LXC: 2.0 versions above and including 2.0.9; 3.0 versions above and including 3.0.0, prior to 3.0.2.

Record
DEBIAN-CVE-2018-6556
CVSS 3.0
3.3 LowCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
OSVUBUNTU-CVE-2018-6556 3.3

lxc-user-nic when asked to delete a network interface will unconditionally open a user provided path. This code path may be used by an unprivileged user to check for the existence of a path which they wouldn't otherwise be able to reach. It may also be used to trigger side effects by causing a (read-only) open of special kernel files (ptmx, proc, sys). Affected releases are LXC: 2.0 versions above and including 2.0.9; 3.0 versions above and including 3.0.0, prior to 3.0.2.

Record
UBUNTU-CVE-2018-6556
CVSS 3.0
3.3 LowCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
OSVopenSUSE-SU-2019:1227-1 No score

Security update for lxc, lxcfs

This update for lxc, lxcfs to version 3.1.0 fixes the following issues:

Security issues fixed:

  • CVE-2019-5736: Fixed a container breakout vulnerability (boo#1122185).
  • CVE-2018-6556: Enable setuid bit on lxc-user-nic (boo#988348).

Non-security issues fixed:

Record
openSUSE-SU-2019:1227-1
Updated
2026-11-02
OSVopenSUSE-SU-2019:1230-1 No score

Security update for lxc

This update for lxc fixes the following issues:

The following security vulnerability was fixed:

  • CVE-2018-6556: Fixed an information leak and possible open() side effects to regular users via lxc-user-nic (boo#988348)

This update was imported from the openSUSE:Leap:15.0:Update update project.

Record
openSUSE-SU-2019:1230-1
Updated
2026-11-02
OSVopenSUSE-SU-2019:1275-1 No score

Security update for lxc, lxcfs

This update for lxc, lxcfs to version 3.1.0 fixes the following issues:

Security issues fixed:

  • CVE-2019-5736: Fixed a container breakout vulnerability (boo#1122185).
  • CVE-2018-6556: Enable setuid bit on lxc-user-nic (boo#988348).

Non-security issues fixed:

Record
openSUSE-SU-2019:1275-1
Updated
2026-11-02
OSVopenSUSE-SU-2024:11030-1 No score

liblxc-devel-4.0.9-1.1 on GA media

These are all security issues fixed in the liblxc-devel-4.0.9-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:11030-1
Updated
2026-11-02
OSVUSN-3730-1 No score

lxc vulnerability

Matthias Gerstner discovered that LXC incorrectly handled the lxc-user-nic utility. A local attacker could possibly use this issue to open arbitrary files.

Record
USN-3730-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
lxc
Alpine:v3.10
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.11
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.12
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.13
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.14
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.15
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.16
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.17
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.18
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.19
 2.0.0 up to 2.1.1-r9
2.1.1-r9
Show 19 moreShow less
Affected packages
PackageAffectedFixed
lxc
Alpine:v3.20
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.21
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.22
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.23
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.24
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.6
 2.0.0 up to 2.0.9-r1
2.0.9-r1
lxc
Alpine:v3.7
 2.0.0 up to 2.1.1-r3
2.1.1-r3
lxc
Alpine:v3.8
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Alpine:v3.9
 2.0.0 up to 2.1.1-r9
2.1.1-r9
lxc
Debian:12
 before 1:2.0.9-6.1
1:2.0.9-6.1
lxc
Debian:13
 before 1:2.0.9-6.1
1:2.0.9-6.1
lxc
Debian:14
 before 1:2.0.9-6.1
1:2.0.9-6.1
lxc
Ubuntu:18.04:LTS
 before 3.0.1-0ubuntu1~18.04.2, plus listed versions
2.1.0-0ubuntu12.1.1-0ubuntu13.0.0~beta1-0ubuntu33.0.0~beta2-0ubuntu23.0.0~beta3-0ubuntu1
Show 4 moreShow less
3.0.0~beta4-0ubuntu13.0.0-0ubuntu13.0.0-0ubuntu23.0.1-0ubuntu1~18.04.1
3.0.1-0ubuntu1~18.04.2
lxc
SUSE:Package Hub 15
From an advisory covering 2 CVEs
 before 3.1.0-bp150.5.3.1
3.1.0-bp150.5.3.1
lxcfs
SUSE:Package Hub 15
From an advisory covering 2 CVEs
 before 3.0.3-bp150.3.3.1
3.0.3-bp150.3.3.1
lxc
SUSE:Package Hub 15
 before 2.0.9-bp150.5.6.1
2.0.9-bp150.5.6.1
lxc
openSUSE:Leap 15.0
From an advisory covering 2 CVEs
 before 3.1.0-lp150.2.10.1
3.1.0-lp150.2.10.1
lxcfs
openSUSE:Leap 15.0
From an advisory covering 2 CVEs
 before 3.0.3-lp150.2.3.1
3.0.3-lp150.2.3.1
lxc
openSUSE:Tumbleweed
From an advisory covering 3 CVEs
 before 4.0.9-1.1
4.0.9-1.1

History

History
RecordedChangedSources
affected, facts
aliases, productsEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2018-6556 is a low vulnerability (CVSS 3.3) in Linuxcontainers Lxc, published August 6, 2018. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.35%, the 28th percentile. Fixed in lxc 2.1.1-r9.

References

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