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High, CVSS 8.6

Rancher's Failure to delete orphaned role bindings does not revoke project level access from group based authentication

CVE-2021-36775GHSA-28g7-896h-695v

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/rancher/rancher 2.6.3, 2.5.12, 2.4.18), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.6 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2021-36775: 0.97% estimated exploitation activity in the next 30 days; percentile 61.94 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Impact This vulnerability only affects customers using group based authentication in Rancher versions up to and including 2.4.17, 2.5.11 and 2.6.2. When removing a Project Role associated to a group from a project, the bindings that grant access to cluster scoped resources for those subjects do not get deleted. This happens due to an incomplete authorization logic check. A user who is a member of an affected group with authenticated access to Rancher could use this to access resources they should no longer have access to. The exposure level will depend on the original permission level granted to the affected project role. Patches Patched versions include releases 2.4.18, 2.5.12, 2.6.3 and later versions. Workarounds Limit access in Rancher to trusted users. There is not a direct mitigation besides upgrading to the patched Rancher versions. References Cluster and project roles documentation for Rancher 2.6, 2.5 and 2.4. For more information If you have any questions or comments about…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-28g7-896h-695v

Agent brief

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# Patch Next advisory brief: CVE-2021-36775

Advisory: Rancher's Failure to delete orphaned role bindings does not revoke project level access from group based authentication
IDs: CVE-2021-36775, GHSA-28g7-896h-695v
Record: https://patchnext.com/advisories/cve-2021-36775 (revision 1, source checked 26 Oct 2026, 15:04 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/rancher/rancher 2.6.3, 2.5.12, 2.4.18. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/rancher/rancher: affected <= 2.4.17; >= 2.5.0, <= 2.5.11; >= 2.6.0, <= 2.6.2; fixed in 2.4.18, 2.5.12, 2.6.3

## Suggested inspection (read-only)
- Go github.com/rancher/rancher: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/rancher/rancher.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-28g7-896h-695v (GitHub-reviewed advisory GHSA-28g7-896h-695v lists affected ranges: Go github.com/rancher/rancher >=0 =2.5.0 =2.6.0 <=2.6.2)

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