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CVE-2026-41050 — Vulnerability in github.com/rancher/fleet — CVE...

CRITICAL

Fleet: Helm impersonation bypass of `RESTClientGetter` retains `cluster-admin` during template rendering

Published May 7, 2026Updated June 25, 2026Source: osv

Summary

### Impact Fleet's Helm deployer did not fully apply ServiceAccount impersonation in two code paths, allowing a tenant with git push access to a Fleet-monitored repository to read secrets from any namespace on every downstream cluster targeted by their `GitRepo`. **Helm `lookup` bypass:** The Helm template engine ran Kubernetes API queries with the fleet-agent's cluster-admin credentials instead of the impersonated ServiceAccount. A chart template could therefore access resources beyond the tenant's RBAC scope. **`valuesFrom` bypass:** Secret and ConfigMap references in `fleet.yaml` `helm.valuesFrom` were read using the fleet-agent's cluster-admin client. A tenant could reference resources in namespaces the impersonated ServiceAccount has no access to. Both issues break Fleet's multi-tenant impersonation boundary. The leaked credentials may belong to external services, making the full impact non-deterministic. Single-tenant deployments where all users are trusted are not affected. **Important:** - For the exposure of additional credentials, the final impact severity for confidentiality, integrity and availability is dependent on the permissions the leaked credentials have on their services. - It is recommended to review for potentially leaked credentials in this scenario and to change them if deemed necessary. Please consult the associated [MITRE ATT&CK - Technique - Account Access Removal](https://attack.mitre.org/techniques/T1531/) for further information about this category of attack. ### Patches Both issues are fixed by ensuring the Helm action configuration consistently uses the impersonated ServiceAccount credentials throughout all Helm operations. Patched versions of Rancher include releases `v2.14.1`, `v2.13.5`, `v2.12.9`, and `v2.11.13`. For Rancher `v2.10.11`, users must manually update their Fleet deployment to version`v0.11.13`. ### Workarounds No workaround fully mitigates the issue for multi-tenant deployments. The patches should be applied as soon as they are available. The following measures reduce the attack surface but do not close either vulnerability: - Restrict git push access to Fleet-monitored repositories to trusted users only. In a multi-tenant setup this removes the precondition entirely, but is often not operationally viable. - Use `GitRepoRestriction` resources to limit which ServiceAccounts each namespace is allowed to use, restricting the set of users who can configure impersonation at all. - Audit deployed chart templates for `lookup` calls and `fleet.yaml` files for cross-namespace `valuesFrom` references as a detective control. ### Resources If there are any questions or comments about this advisory: - Reach out to the [SUSE Rancher Security team](https://github.com/rancher/rancher/security/policy) for security related inquiries. - Open an issue in the [Rancher](https://github.com/rancher/rancher/issues/new/choose) repository. - Verify using the [support matrix](https://www.suse.com/suse-rancher/support-matrix/all-supported-versions/) and [product support lifecycle](https://www.suse.com/lifecycle/).

Advisory Timeline

  • First published May 7, 2026 (158 days ago).
  • Last revised June 25, 2026 — 50 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

Go
Update github.com/rancher/fleet to 0.15.1 or later
go get github.com/rancher/fleet@v0.15.1
Go
Update github.com/rancher/fleet to 0.14.5 or later
go get github.com/rancher/fleet@v0.14.5
Go
Update github.com/rancher/fleet to 0.12.14 or later
go get github.com/rancher/fleet@v0.12.14
Go
Update github.com/rancher/fleet to 0.13.10 or later
go get github.com/rancher/fleet@v0.13.10
Go
Update github.com/rancher/fleet to 0.11.13 or later
go get github.com/rancher/fleet@v0.11.13

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (5)

Affects 1 ecosystem: go (1).

PackageEcosystemAffectedFixed In
github.com/rancher/fleet
go
All versions0.15.1
github.com/rancher/fleet
go
All versions0.14.5
github.com/rancher/fleet
go
All versions0.12.14
github.com/rancher/fleet
go
All versions0.13.10
github.com/rancher/fleet
go
All versions0.11.13

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

  • CWE-863
    Incorrect AuthorizationMITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 9.9 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

Frequently Asked Questions

What is CVE-2026-41050?
Fleet: Helm impersonation bypass of `RESTClientGetter` retains `cluster-admin` during template rendering This vulnerability has been assigned a severity rating of CRITICAL (CVSS score: 9.9/10).
How do I check if my project is affected by CVE-2026-41050?
CVE-2026-41050 affects github.com/rancher/fleet. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-41050 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
9.9

Exploitation is straightforward and causes maximum impact. Patch immediately.

Also Known As

GHSA-765j-qfrp-hm3j
GO-2026-5207

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