GHSA-jwvr-vv7p-gpwq CVE-2021-36784

Privilege escalation for users with create/update permissions in Global Roles in Rancher

High Go

Severity: 6.5 / 10; High · CVSS 3.1
Exploit chance (EPSS): 0.90%; Chance of exploitation in the next 30 days. Higher than 59.75% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-269 Improper Privilege Management; CWE-285 Improper Authorization
Fix: 2.6.4; Upgrade github.com/rancher/rancher to this version or later

Description

Impact

This vulnerability affects customers who utilize non-admin users that are able to create or edit Global Roles. The most common use case for this scenario is the restricted-admin role.

A flaw was discovered in Rancher versions from 2.5.0 up to and including 2.5.12 and from 2.6.0 up to and including 2.6.3 which allows users who have create or update permissions on Global Roles to escalate their permissions, or those of another user, to admin-level permissions. Global Roles grant users Rancher-wide permissions, such as the ability to create clusters. In the identified versions of Rancher, when users are given permission to edit or create Global Roles, they are not restricted to only granting permissions which they already posses.

The privilege escalation can be taken advantage of in two ways by users with create or update permissions on Global Roles (including the restricted-admin):

Editing the global admin role to make it the default for new users, then creating a new user that will be elevated to the global admin role.
Creating a new global role with permissions already possessed by the restricted-admin, assigning this new role to a user, then modifying the global role to grant additional administrive like permissions ('*') to the elevated user.

Patches

Patched versions include releases 2.5.13, 2.6.4 and later versions.

Workarounds

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

Note: If you have users who have create or edit permissions on Global Roles but are not admin users (for example, the restricted-admin), it is highly advised to review the roles and users created by those users for possible privilege escalations.

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	`>= 2.6.0, < 2.6.4`	`2.6.4`
github.com/rancher/rancher	`>= 2.5.0, < 2.5.13`	`2.5.13`

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 3.1 6.5

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H

Attack vector: Network
Attack complexity: Low
Privileges required: High
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: High

Weakness

CWE-269: Improper Privilege Management

The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

How to prevent it

Architecture and Design, Operation: Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
Architecture and Design: Follow the principle of least privilege when assigning access rights to entities in a software system.
Architecture and Design: Consider following the principle of separation of privilege. Require multiple conditions to be met before permitting access to a system resource.

CWE-285: Improper Authorization

The product does not perform or incorrectly performs 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) 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 you perform access control checks related to your business logic. These checks may be different than the access control checks that you apply 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.
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

Advisories

nvd.nist.gov/vuln/detail/CVE-2021-36784

Timeline

May 2, 2022 Published
Jun 17, 2026 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-4j6x-2764-m8gh Rancher has over-inclusive team membership expansion in GitHub App authentication provider	High	Also affects github.com/rancher/rancher
GHSA-vx8h-4prv-g744 Rancher has Privilege Escalation from Project Owner to Host	High	Also affects github.com/rancher/rancher
GHSA-mhc6-2gfq-xx62 Rancher vulnerable to command injection through unsanitized YAML parameter	Critical	Also affects github.com/rancher/rancher
GHSA-5v3h-x4wf-5c35 Rancher Extensions have arbitrary file access via path traversal	High	Also affects github.com/rancher/rancher
GHSA-gqf8-rvrh-g7w6 Rancher cloud credentials can be used through proxy API by users without access	Critical	Also affects github.com/rancher/rancher
GHSA-hwm2-4ph6-w6m5 Rancher's restricted PodSecurityPolicy does not prevent containers from running as a privileged user	High	Also affects github.com/rancher/rancher
GHSA-mc24-7m59-4q5p Rancher CLI skips TLS verification on Rancher CLI login command	Medium	Also affects github.com/rancher/rancher
GHSA-mw39-9qc2-f7mg Rancher exposes sensitive information through audit logs	Medium	Also affects github.com/rancher/rancher

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