LXC up to 7.0.0 liblxc lxc_container::clone symlink

Summaryinfo

A vulnerability, which was classified as very critical, was found in LXC up to 7.0.0. Impacted is the function lxc_container::clone of the component liblxc. Such manipulation leads to symlink. This vulnerability is listed as CVE-2026-100395. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in LXC up to 7.0.0. Affected by this issue is the function lxc_container::clone of the component liblxc. The manipulation with an unknown input leads to a symlink vulnerability. Using CWE to declare the problem leads to CWE-61. The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-100395 since 09/25/2026. The exploitation is known to be easy. The attack may be launched remotely. Additional levels of successful authentication are necessary for exploitation. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 11/05/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Name

• LXC

Version

• 7.0

Website

• Product: https://github.com/lxc/lxc/

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