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CVE-2021-36783 — Vulnerability in github.com/rancher/rancher — CVE...

CRITICAL

Rancher doesn't properly sanitize credentials in cluster template answers

Published March 3, 2026Updated July 8, 2026Source: osv

Summary

### Impact It was discovered that in Rancher versions up to and including 2.5.12 and 2.6.3 there is a failure to properly sanitize credentials in cluster template answers. This failure can lead to plaintext storage and exposure of credentials, passwords and API tokens. The exposed credentials are visible in Rancher to authenticated `Cluster Owners`, `Cluster Members`, `Project Owners` and `Project Members` on the endpoints `/v1/management.cattle.io.clusters`, `/v3/clusters` and `/k8s/clusters/local/apis/management.cattle.io/v3/clusters`. Sensitive fields are now stripped from `Clusters` objects before the object is stored. For objects that existed before this security fix, a one-time migration happens on startup. **Important:** - It is highly advised to review for potential leaked credentials in this scenario, and to change them if deemed necessary. - The final impact severity for confidentiality, integrity and availability is dependent on the permissions that the leaked credentials have on their own services. ### 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. **Important:** It is highly advised to review for potential leaked credentials in this scenario, and to change them if deemed necessary. ### For more information If you have any questions or comments about this advisory: * Reach out to [SUSE Rancher Security team](https://github.com/rancher/rancher/security/policy) for security related inquiries. * Open an issue in [Rancher](https://github.com/rancher/rancher/issues/new/choose) repository. * Verify our [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 March 3, 2026 (223 days ago).
  • Last revised July 8, 2026 — 127 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

Go
Update github.com/rancher/rancher to 2.5.13 or later
go get github.com/rancher/rancher@v2.5.13
Go
Update github.com/rancher/rancher to 2.6.4 or later
go get github.com/rancher/rancher@v2.6.4

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

Affected Packages (2)

Affects 1 ecosystem: go (1).

PackageEcosystemAffectedFixed In
github.com/rancher/rancher
go
All versions2.5.13
github.com/rancher/rancher
go
All versions2.6.4

Vulnerability Classification

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

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-2021-36783?
Rancher doesn't properly sanitize credentials in cluster template answers 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-2021-36783?
CVE-2021-36783 affects github.com/rancher/rancher. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2021-36783 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-8w87-58w6-hfv8

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