# CVE-2018-6556: liblxc1: lxc-user-nic when asked to delete a network interface will unconditionally open a user provided path

CVE-2018-6556 is fixed in 6 products on 1 platform, first by liblxc-common 3.0.1-0ubuntu1~18.04.2, released August 6, 2018. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2018-6556
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.0035
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 6, 2018

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | liblxc-common Ubuntu 18.04.6 LTS (bionic) | 3.0.1-0ubuntu1~18.04.2 | [liblxc-common 3.0.1-0ubuntu1~18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-liblxc-common-3.0.1-0ubuntu1-18.04.2.md) | Aug 6, 2018 |
| Linux | liblxc1 Ubuntu 18.04.6 LTS (bionic) | 3.0.1-0ubuntu1~18.04.2 | [liblxc1 3.0.1-0ubuntu1~18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-liblxc1-3.0.1-0ubuntu1-18.04.2.md) | Aug 6, 2018 |
| Linux | libpam-cgfs Ubuntu 18.04.6 LTS (bionic) | 3.0.1-0ubuntu1~18.04.2 | [libpam-cgfs 3.0.1-0ubuntu1~18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libpam-cgfs-3.0.1-0ubuntu1-18.04.2.md) | Aug 6, 2018 |
| Linux | lxc Ubuntu 18.04.6 LTS (bionic) | 3.0.1-0ubuntu1~18.04.2 | [lxc 3.0.1-0ubuntu1~18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-lxc-3.0.1-0ubuntu1-18.04.2.md) | Aug 6, 2018 |
| Linux | lxc-utils Ubuntu 18.04.6 LTS (bionic) | 3.0.1-0ubuntu1~18.04.2 | [lxc-utils 3.0.1-0ubuntu1~18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-lxc-utils-3.0.1-0ubuntu1-18.04.2.md) | Aug 6, 2018 |
| Linux | lxc1 Ubuntu 18.04.6 LTS (bionic) | 3.0.1-0ubuntu1~18.04.2 | [lxc1 3.0.1-0ubuntu1~18.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-lxc1-3.0.1-0ubuntu1-18.04.2.md) | Aug 6, 2018 |

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Data as of 2026-11-07T12:40:37Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo