# CVE-2026-100395: LXC: lxc-copy host-context hostname update follows symlink

Status: published. Published: 2026-11-05. Updated: 2026-11-05.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- lxc / lxc: <= 7.0.0 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 4.0: 6.8 (medium); 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; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-59, CWE-61

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/lxc/lxc/security/advisories/GHSA-r23j-58gg-pjjc (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/lxc/lxc/commit/6424a91a55efc54edc25ca46e9165bd9f35b50b7 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/lxc/lxc/commit/fa12709a79c2b63b3918297d7505108fcc840eb6 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-100395; retrieved 2026-11-05; source updated 2026-11-05

Revision: 40718f704104358b3953ec45460a0bc05fa96e187831ae8cf19bf731e93dcb0f

Canonical: https://y2.dev/cve/CVE-2026-100395

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