9.4

CVSS Score

4.0

-

CVSS Score

Basic Information

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CVE-2026-44939

CVE-2026-44939: Command injection through unsanitized YAML parameter in Rancher

A command injection vulnerability in the Rancher Manager cluster before 2.14.2 import endpoint /v3/import/{token}_{clusterId}.yaml through unsanitized YAML parameters could allow remote attackers to break out of an image, and execute e.g. malicious containers.

(GitHub Advisory)

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CVE-2026-44939

CVE-2026-44939:

9.4

CVSS Score

4.0

-

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/rancher	go	>= 2.14.0, < 2.14.2	2.14.2
github.com/rancher/rancher	go	>= 2.13.0, < 2.13.6	2.13.6
github.com/rancher/rancher	go	>= 2.12.0, < 2.12.10	2.12.10
github.com/rancher/rancher	go	>= 2.11.0, < 2.11.14	2.11.14
github.com/rancher/rancher	go	>= 2.10.0, < 2.10.12	2.10.12
github.com/rancher/rancher	go	< 0.0.0-20260617231817-2aa77eb283e7	0.0.0-20260617231817-2aa77eb283e7

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability lies in the Rancher Manager cluster import endpoint /v3/import/{token}_{clusterId}.yaml, which accepts an authImage query parameter. The analysis of the provided patch commit 2aa77eb283e7 reveals that the function ClusterImport.ClusterImportHandler in pkg/api/norman/customization/clusterregistrationtokens/import.go is responsible for handling this endpoint. Before the patch, the authImage parameter was taken directly from the user request and used in a template to generate a Kubernetes manifest without proper validation. This allowed an attacker to craft a malicious authImage value with URL-encoded newlines to inject arbitrary YAML, leading to command execution on the cluster. The patch introduces a new validation function, validateAuthImage, which uses reference.ParseNormalizedNamed to ensure the authImage parameter is a valid OCI image reference. The ClusterImportHandler was modified to call this validation function immediately after retrieving the authImage parameter, thus mitigating the vulnerability. Therefore, ClusterImport.ClusterImportHandler is the vulnerable function as it was the one processing the unsanitized, malicious input.

Vulnerable functions

ClusterImport.ClusterImportHandler

pkg/api/norman/customization/clusterregistrationtokens/import.go

This function is an HTTP handler for the cluster import endpoint. It processes the `authImage` query parameter. Before the patch, this parameter was not sanitized, allowing an attacker to inject newlines and other characters to break out of the YAML `image:` field and insert arbitrary, malicious commands into the generated Kubernetes manifest. The patch adds a call to `validateAuthImage` to sanitize this input, confirming that this handler was the entry point for the vulnerability.

Vulnerability Intelligence
Miggo AI

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WAF Rule

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Reasoning

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