8.8

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2026-44938

CVE-2026-44938: Fleet has PSS Bypass through addLabelsFromOptions in Fleet Agent

A vulnerability has been identified in Fleet's agent-side deployer, which did not filter security-sensitive keys from namespaceLabels in fleet.yaml (or BundleDeployment.spec.options.namespaceLabels) when applying them to the target namespace.

An attacker with git push access to a Fleet-monitored repository could overwrite Pod Security Standards (PSS) enforcement labels on a target namespace. This allows the attacker to weaken admission controls and deploy workloads that PSS policies would otherwise block.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2026-44938

CVE-2026-44938:

8.8

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

SSVC / BOD 26-04 ↗

Exploitation NoneAutomatable NoTech Impact Total

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Package Name	Ecosystem	Vulnerable Versions	First Patched Version
github.com/rancher/fleet	go	>= 0.15.0, < 0.15.2	0.15.2
github.com/rancher/fleet	go	>= 0.14.0, < 0.14.6	0.14.6
github.com/rancher/fleet	go	>= 0.13.0, < 0.13.11	0.13.11
github.com/rancher/fleet	go	>= 0.12.0, < 0.12.15	0.12.15

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability, identified as GHSA-864g-863m-vcvq, allows an attacker with git push access to a Fleet-monitored repository to bypass Pod Security Standards (PSS) by overwriting PSS enforcement labels on a target namespace. The root cause lies in the Fleet agent's deployer, which failed to sanitize user-provided namespace labels.

The analysis of the patches between vulnerable version v0.15.1 and patched version v0.15.2 pinpointed the vulnerable code. The key changes are in the internal/cmd/agent/deployer/deployer.go file.

The function addLabelsFromOptions was identified as the primary vulnerable function. Before the patch, it would take all labels defined in fleet.yaml (via BundleDeployment.spec.options.namespaceLabels) and apply them to the target namespace, removing any pre-existing labels not specified in the options. This allowed an attacker to inject or modify labels with the pod-security.kubernetes.io/ prefix, effectively weakening the namespace's security policy.

The patch, introduced in commit 74f2dc9fb0d98450962e1d885a1d10f0e28abf01, rectifies this by modifying addLabelsFromOptions to explicitly ignore any labels with the pod-security.kubernetes.io/ prefix from the user-provided options and to preserve any such labels that already exist on the namespace object. This ensures that PSS labels remain under the control of the cluster administrator.

The Deployer.setNamespaceLabelsAndAnnotations method is the direct caller of addLabelsFromOptions and is therefore a critical part of the vulnerable execution path. It reads the malicious labels from the BundleDeployment and passes them to addLabelsFromOptions for processing.

Vulnerable functions

deployer.addLabelsFromOptions

internal/cmd/agent/deployer/deployer.go

This function was vulnerable because it did not filter security-sensitive labels, such as those related to Pod Security Standards (PSS). It would apply all labels from the `fleet.yaml` configuration, allowing an attacker to overwrite or remove critical PSS labels on a namespace. The patch adds checks to ignore any labels with the `pod-security.kubernetes.io/` prefix from the user-provided options and to preserve existing PSS labels on the namespace.

deployer.Deployer.setNamespaceLabelsAndAnnotations

internal/cmd/agent/deployer/deployer.go

This method orchestrates the process of applying labels and annotations to a namespace. It calls the vulnerable `addLabelsFromOptions` function, passing the user-controlled labels from the `BundleDeployment` options. Therefore, this function is a key part of the execution flow that leads to the vulnerability being triggered.

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WAF Rule

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Reasoning

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