Arbitrary file write on LXD host via symlink in migration stream

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-87799
StatePUBLISHED
Assignercanonical
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-28 14:17:21 UTC
Updated2026-09-29 04:18:01 UTC
DescriptionImproper link resolution in the migration receive path in Canonical LXD versions 4.0 and later (fixed in 4.0.14, 5.0.10, 5.21.8 and 6.10) on Linux allows an authenticated client that can create instances or custom storage volumes in a project, or a malicious migration source server, to write attacker-controlled files to arbitrary paths on the target host as root, leading to full host compromise. The attacker does this with a crafted rsync or btrfs send stream that plants a symlink in the transferred volume, such as rootfs or root.img, and then writes through it.

Risk And Classification

Primary CVSS: v3.1 9.9 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS: 0.004070000 probability, percentile 0.323850000 (date 2026-09-29)

Problem Types: CWE-59 | CWE-59 CWE-59 Improper link resolution before file access ('link following')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary9.9CRITICALCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
3.1CNACVSS9.9CRITICALCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Canonical LXD affected 4.0.0 4.0.14 semver Linux
CNA Canonical LXD affected 5.0.0 5.0.10 semver Linux
CNA Canonical LXD affected 5.21.0 5.21.8 semver Linux
CNA Canonical LXD affected 6.0 6.10 semver Linux

References

ReferenceSourceLinkTags
github.com/canonical/lxd/security/advisories/GHSA-fmc3-3cpq-6whr [email protected] github.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

Solutions

CNA: Upgrade to LXD versions 4.0.14, 5.0.10, 5.21.8, 6.10 or later.

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