Rancher has over-inclusive team membership expansion in GitHub App authentication provider

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-41053: 0.52% estimated exploitation activity in the next 30 days; percentile 44.49 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact A vulnerability has been identified within Rancher Manager in the GitHub App authentication provider. When evaluating permissions, the provider incorrectly expands user team memberships to include all teams within the associated GitHub organization, rather than restricting access to the specific teams to which the user actually belongs. Specifically, when a user authenticates via the GitHub App provider, Rancher's team membership evaluation logic incorrectly handles cached data. Instead of checking the user-specific list, the evaluation logic iterates over all teams defined within the entire GitHub organization. The authentication provider should consult the correctly cached, per-user membership list to assign the user's specific group permissions. Consequently, any authenticated user who belongs to at least one team in a GitHub organization is mistakenly granted group principals for every team within that entire organization during authentication and authorization checks.…

Published by the source

1 Jul 2026, 20:51 UTC

Last modified by the source

1 Jul 2026, 20:51 UTC

Source last checked

26 Oct 2026, 15:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-4j6x-2764-m8gh

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# Patch Next advisory brief: CVE-2026-41053

Advisory: Rancher has over-inclusive team membership expansion in GitHub App authentication provider
IDs: CVE-2026-41053, GHSA-4j6x-2764-m8gh
Record: https://patchnext.com/advisories/cve-2026-41053 (revision 1, source checked 26 Oct 2026, 15:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
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 2.14.2, 2.13.6, 0.0.0-20260519172014-d0c047bbc6d2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/rancher/rancher: affected >= 2.14.0, < 2.14.2; >= 2.13.0, < 2.13.6; < 0.0.0-20260519172014-d0c047bbc6d2; fixed in 0.0.0-20260519172014-d0c047bbc6d2, 2.14.2, 2.13.6

## 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-4j6x-2764-m8gh (GitHub-reviewed advisory GHSA-4j6x-2764-m8gh lists affected ranges: Go github.com/rancher/rancher >=2.14.0 =2.13.0 =0 <0.0.0-20260519172014-d0c047bbc6d2)

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