What is CVE-2021-36782?

CVE-2021-36782 is a critical-severity security vulnerability in github.com/rancher/rancher (go), affecting versions >= 2.5.0, < 2.5.16. It is fixed in 2.5.16, 2.6.7.

How severe is CVE-2021-36782?

CVE-2021-36782 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/rancher/rancher are affected by CVE-2021-36782?

github.com/rancher/rancher (go) versions >= 2.5.0, < 2.5.16 is affected.

Is there a fix for CVE-2021-36782?

Yes. CVE-2021-36782 is fixed in 2.5.16, 2.6.7. Upgrade to this version or later.

Is CVE-2021-36782 exploitable, and should I be worried?

Whether CVE-2021-36782 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.

What actually determines whether CVE-2021-36782 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-2021-36782?

Upgrade: github.com/rancher/rancher to 2.5.16 or later, github.com/rancher/rancher to 2.6.7 or later.

CVE-2021-36782 in github.com/rancher/rancher

Q: How severe is CVE-2021-36782?

CVE-2021-36782 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.

Q: Which versions of github.com/rancher/rancher are affected by CVE-2021-36782?

github.com/rancher/rancher (go) versions >= 2.5.0, < 2.5.16 is affected.

Q: Is there a fix for CVE-2021-36782?

Yes. CVE-2021-36782 is fixed in 2.5.16, 2.6.7. Upgrade to this version or later.

Q: Is CVE-2021-36782 exploitable, and should I be worried?

Whether CVE-2021-36782 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.

Q: What actually determines whether CVE-2021-36782 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.

Q: How do I fix CVE-2021-36782?

Upgrade: github.com/rancher/rancher to 2.5.16 or later, github.com/rancher/rancher to 2.6.7 or later.

Summary

Rancher API and cluster.management.cattle.io object vulnerable to plaintext storage and exposure of credentials

Workarounds

Limit access in Rancher to trusted users. There is not a direct mitigation besides upgrading to the patched Rancher versions.

Important:

It is highly advised to rotate Rancher's serviceAccountToken. This rotation is not done by the version upgrade. Please see the helper script below.
The local and downstream clusters should be checked for potential unrecognized services (pods), users and API keys.
It is recommended to review for potential leaked credentials in this scenario, that are not directly related to Rancher, and to change them if deemed necessary.

The script available in rancherlabs/support-tools/rotate-tokens repository can be used as a helper to rotate the service account token (used to provision clusters). The script requires a valid Rancher API token, kubectl access to the local cluster and the jq command.

Credits

We would like to recognize and appreciate Florian Struck (from Continum AG) and Marco Stuurman (from Shock Media B.V.) for the responsible disclosure of this security issue.

For more information

If you have any questions or comments about this advisory:

Reach out to SUSE Rancher Security team for security related inquiries.
Open an issue in Rancher repository.
Verify our support matrix and product support lifecycle.

Impact

An issue was discovered in Rancher versions up to and including 2.5.15 and 2.6.6 where sensitive fields, like passwords, API keys and Rancher's service account token (used to provision clusters), were stored in plaintext directly on Kubernetes objects like Clusters, for example cluster.management.cattle.io. Anyone with read access to those objects in the Kubernetes API could retrieve the plaintext version of those sensitive data.

The exposed credentials are visible in Rancher to authenticated Cluster Owners, Cluster Members, Project Owners, Project Members and User Base on the endpoints:

/v1/management.cattle.io.catalogs
/v1/management.cattle.io.cluster
/v1/management.cattle.io.clustertemplates
/v1/management.cattle.io.notifiers
/v1/project.cattle.io.sourcecodeproviderconfig
/k8s/clusters/local/apis/management.cattle.io/v3/catalogs
/k8s/clusters/local/apis/management.cattle.io/v3/clusters
/k8s/clusters/local/apis/management.cattle.io/v3/clustertemplates
/k8s/clusters/local/apis/management.cattle.io/v3/notifiers
/k8s/clusters/local/apis/project.cattle.io/v3/sourcecodeproviderconfigs

Sensitive fields are now stripped from Clusters and other objects and moved to a Secret before the object is stored. The Secret is retrieved when the credential is needed. For objects that existed before this security fix, a one-time migration happens on startup.

Important:

The exposure of Rancher's serviceAccountToken allows any standard user to escalate its privileges to cluster administrator in Rancher.
For the exposure of credentials not related to Rancher, the final impact severity for confidentiality, integrity and availability is dependent on the permissions that the leaked credentials have on their own services.

The fields that have been addressed by this security fix are:

Notifier.SMTPConfig.Password
Notifier.WechatConfig.Secret
Notifier.DingtalkConfig.Secret
Catalog.Spec.Password
SourceCodeProviderConfig.GithubPipelineConfig.ClientSecret
SourceCodeProviderConfig.GitlabPipelineConfig.ClientSecret
SourceCodeProviderConfig.BitbucketCloudPipelineConfig.ClientSecret
SourceCodeProviderConfig.BitbucketServerPipelineConfig.PrivateKey
Cluster.Spec.RancherKubernetesEngineConfig.BackupConfig.S3BackupConfig.SecretKey
Cluster.Spec.RancherKubernetesEngineConfig.PrivateRegistries.Password
Cluster.Spec.RancherKubernetesEngineConfig.Network.WeaveNetworkProvider.Password
Cluster.Spec.RancherKubernetesEngineConfig.CloudProvider.VsphereCloudProvider.Global.Password
Cluster.Spec.RancherKubernetesEngineConfig.CloudProvider.VsphereCloudProvider.VirtualCenter.Password
Cluster.Spec.RancherKubernetesEngineConfig.CloudProvider.OpenstackCloudProvider.Global.Password
Cluster.Spec.RancherKubernetesEngineConfig.CloudProvider.AzureCloudProvider.AADClientSecret
Cluster.Spec.RancherKubernetesEngineConfig.CloudProvider.AzureCloudProvider.AADClientCertPassword
Cluster.Status.ServiceAccountToken
ClusterTemplate.Spec.ClusterConfig.RancherKubernetesEngineConfig.PrivateRegistries.Password
ClusterTemplate.Spec.ClusterConfig.RancherKubernetesEngineConfig.Network.WeaveNetworkProvider.Password
ClusterTemplate.Spec.ClusterConfig.RancherKubernetesEngineConfig.CloudProvider.VsphereCloudProvider.Global.Password
ClusterTemplate.Spec.ClusterConfig.RancherKubernetesEngineConfig.CloudProvider.VsphereCloudProvider.VirtualCenter.Password
ClusterTemplate.Spec.ClusterConfig.RancherKubernetesEngineConfig.CloudProvider.OpenstackCloudProvider.Global.Password
ClusterTemplate.Spec.ClusterConfig.RancherKubernetesEngineConfig.CloudProvider.AzureCloudProvider.AADClientSecret
ClusterTemplate.Spec.ClusterConfig.RancherKubernetesEngineConfig.CloudProvider.AzureCloudProvider.AADClientCertPassword

CVE-2021-36782 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 (2.5.16, 2.6.7); upgrading removes the vulnerable code path.

Affected versions

github.com/rancher/rancher (>= 2.5.0, < 2.5.16) github.com/rancher/rancher (>= 2.6.0, < 2.6.7)

Security releases

github.com/rancher/rancher → 2.5.16 (go) github.com/rancher/rancher → 2.6.7 (go)

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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See it in your environment New to Kodem? Get a demo →

Remediation advice

Patched versions include releases 2.5.16, 2.6.7 and later versions.

After upgrading to a patched version, it is important to check for the SecretsMigrated condition on Clusters, ClusterTemplates, and Catalogs to confirm when secrets have been fully migrated off of those objects and the objects scoped within them (Notifiers and SourceCodeProviderConfigs).

Frequently Asked Questions

What is CVE-2021-36782? CVE-2021-36782 is a critical-severity security vulnerability in github.com/rancher/rancher (go), affecting versions >= 2.5.0, < 2.5.16. It is fixed in 2.5.16, 2.6.7.
How severe is CVE-2021-36782? CVE-2021-36782 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/rancher/rancher are affected by CVE-2021-36782? github.com/rancher/rancher (go) versions >= 2.5.0, < 2.5.16 is affected.
Is there a fix for CVE-2021-36782? Yes. CVE-2021-36782 is fixed in 2.5.16, 2.6.7. Upgrade to this version or later.
Is CVE-2021-36782 exploitable, and should I be worried? Whether CVE-2021-36782 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-2021-36782 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-2021-36782?
- Upgrade github.com/rancher/rancher to 2.5.16 or later
- Upgrade github.com/rancher/rancher to 2.6.7 or later

Other vulnerabilities in github.com/rancher/rancher

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