GHSA-hwm2-4ph6-w6m5 GO-2026-4590
Rancher's restricted PodSecurityPolicy does not prevent containers from running as a privileged user
- Severity
- 0.0 / 10
- High · CVSS 4.0
- Exploit chance (EPSS)
- —
- No score published
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-862 Missing Authorization
- Fix
2.6.4- Upgrade github.com/rancher/rancher to this version or later
Description
Impact
The restricted pod security policy (PSP), provided in Rancher versions from 2.0 up to and including 2.6.3, has a deviation from the upstream restricted policy provided in Kubernetes, in which Rancher's PSP has runAsUser set to runAsAny, while upstream has runAsUser set to MustRunAsNonRoot. This allows containers to run as any user, including a privileged user (root), even when Rancher's restricted policy is enforced on a project or at cluster level.
A new restricted-noroot PSP was created to prevent pods from running as root when this policy is enforced. This new policy was introduced, instead of patching the current provided restricted policy, in order to avoid breaking users' workloads that are using the restricted PSP and that might be running as a privileged user.
Note: Running containers as root increases the risk of a compromised container being used by a malicious actor as an attack platform to further exploit the user's environment. It is a security best practice to avoid running containers as a privileged user and to limit its usage to workloads where it is strictly necessary.
Patches
Patched versions include release 2.6.4 and later versions. The existing restricted PSP in Rancher 2.6.4 was not modified and still allows containers to run as a privileged user, as explained above. This fix was not backported to previous releases.
For Rancher 2.6.4 and later releases, users using the current restricted PSP and that want to prevent containers from running as root, are advised to migrate to the new restricted-noroot policy. Before doing this migration, it is necessary to verify if affected workloads are currently running as a privileged user and modify them accordingly to the users' own environment to run as a non-privileged user. A redeployment of the affected workload is necessary in order for the new PSP to take effect.
Workarounds
For users running Rancher 2.6.3 and previous releases, which did not received this backport and that want to benefit from this fix, they can manually create a new restricted-noroot PSP on their clusters through Rancher UI. The template of the restricted-noroot policy provided in Rancher 2.6.4 is available in the source code. As a reminder, it is also necessary to manually verify and redeploy the running workload before enabling a more restricted pod security policy.
References
For instructions on how to configure pod security policies using Rancher, please refer to the documentation page. For more information on PSPs in Kubernetes, please refer to the Kubernetes documentation (permalink).
Important reminder: Pod security policies are considered deprecated since Kubernetes v1.21, and will be removed in Kubernetes v1.25. Consult Kubernetes' documentation (permalink) regarding how to migrate from PodSecurityPolicy to Kubernetes' built-in PodSecurity Admission Controller. For the list of supported Kubernetes versions in Rancher, please consult our support matrix.
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.
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| github.com/rancher/rancher | >= 2.0.0, < 2.6.4 |
2.6.4 |
| github.com/rancher/rancher | >= 2.0.0+incompatible |
No fix yet |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
github.com/rancher/rancher Go → 2.6.4
- go
go get github.com/rancher/rancher@v2.6.4 && go mod tidy
Severity breakdown
CVSS 4.0 0.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- None
- Privileges required
- Low
- User interaction
- None
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- High
- Availability (vulnerable system)
- None
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
Weakness
CWE-862: Missing Authorization
The product does not perform an authorization check when an actor attempts to access a resource or perform an action.
How to prevent it
- Architecture and Design: Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
- Architecture and Design: Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor [REF-7].
- Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
- Architecture and Design: For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page. One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.
- System Configuration, Installation: Use the access control capabilities of your operating system and server environment and define your access control lists accordingly. Use a "default deny" policy when defining these ACLs.
References
Packages
Other links
Timeline
- Published
- Last updated by the source
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