Description
LXC is a userspace interface for the Linux kernel containment features used to create and manage system containers. In LXC 7.0.0 and earlier, lxc-copy and the public liblxc clone() API can follow attacker-controlled symbolic links while updating /etc/hostname in a copied container root filesystem. The affected surfaces are lxc-copy and liblxc's public lxc_container::clone() API. The privileged cloning process must run as root. The source rootfs must be attacker-controlled or less trusted. A symlink can be placed at etc/hostname or in an intermediate component. The clone operation preserves the symlink before updating the hostname. The vulnerable write truncates and overwrites an existing file outside the destination rootfs. When root clones an untrusted container without LXC_CLONE_KEEPNAME, the copied symlink can resolve outside the destination rootfs and cause the privileged process to overwrite an existing host file with the destination container name. Unprivileged use and managers with independent cloning implementations are not affected. LXC_CLONE_KEEPNAME avoids the hostname update and therefore the affected write.
Published: 2026-11-05
Score: 6.8 Medium
EPSS: n/a
KEV: No
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History

Thu, 05 Nov 2026 22:00:00 +0000

Type Values Removed Values Added
Description LXC is a userspace interface for the Linux kernel containment features used to create and manage system containers. In LXC 7.0.0 and earlier, lxc-copy and the public liblxc clone() API can follow attacker-controlled symbolic links while updating /etc/hostname in a copied container root filesystem. The affected surfaces are lxc-copy and liblxc's public lxc_container::clone() API. The privileged cloning process must run as root. The source rootfs must be attacker-controlled or less trusted. A symlink can be placed at etc/hostname or in an intermediate component. The clone operation preserves the symlink before updating the hostname. The vulnerable write truncates and overwrites an existing file outside the destination rootfs. When root clones an untrusted container without LXC_CLONE_KEEPNAME, the copied symlink can resolve outside the destination rootfs and cause the privileged process to overwrite an existing host file with the destination container name. Unprivileged use and managers with independent cloning implementations are not affected. LXC_CLONE_KEEPNAME avoids the hostname update and therefore the affected write.
Title LXC: lxc-copy host-context hostname update follows symlink
Weaknesses CWE-59
CWE-61
References
Metrics cvssV4_0

{'score': 6.8, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N'}

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-11-05T21:45:58.175Z

Reserved: 2026-09-25T20:08:33.083Z

Link: CVE-2026-100395

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-05T22:17:41.803

Modified: 2026-11-05T22:17:41.803

Link: CVE-2026-100395

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

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Weaknesses
  • CWE-59

    Improper Link Resolution Before File Access ('Link Following')

  • CWE-61

    UNIX Symbolic Link (Symlink) Following