LXC: lxc-copy host-context hostname update follows symlink

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-100395
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-05 22:17:41 UTC
Updated2026-11-09 18:17:18 UTC
DescriptionLXC 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.

Risk And Classification

Primary CVSS: v4.0 6.8 MEDIUM from [email protected]

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.001510000 probability, percentile 0.042870000 (date 2026-11-09)

Problem Types: CWE-59 | CWE-61 | CWE-59 CWE-59: Improper Link Resolution Before File Access ('Link Following') | CWE-61 CWE-61: UNIX Symbolic Link (Symlink) Following

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary6.8MEDIUMCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/C...
4.0CNADECLARED6.8MEDIUMCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
Active
Confidentiality
None
Integrity
High
Availability
High
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Lxc Lxc affected <= 7.0.0 Not specified

References

ReferenceSourceLinkTags
github.com/lxc/lxc/commit/fa12709a79c2b63b3918297d7505108fcc840eb6 [email protected] github.com
github.com/lxc/lxc/security/advisories/GHSA-r23j-58gg-pjjc [email protected] github.com
github.com/lxc/lxc/commit/6424a91a55efc54edc25ca46e9165bd9f35b50b7 [email protected] github.com
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