CVE-2026-66795

Managedcluster-import-controller: csr auto-approver does not validate certificate subject or signername (spoke→hub cluster-admin)

Published Aug 17, 2026 CVSS 3.1 · 9.9 Critical EPSS < 1% KEV · Not listed
Description
A flaw was found in the managedcluster-import-controller. The Certificate Signing Request (CSR) auto-approval logic improperly validates incoming CSRs, specifically by not inspecting the signer name or decoding the PEM-encoded x509 CSR. This vulnerability allows a privileged service account on a spoke cluster to submit a malicious CSR. Successful exploitation can lead to privilege escalation, enabling the attacker to obtain administrative credentials on the hub cluster.

Remediation

Vendor Workaround

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Title Managedcluster-import-controller: managedcluster-import-controller: csr auto-approver does not validate certificate subject, signername, or requester identity Managedcluster-import-controller: csr auto-approver does not validate certificate subject or signername (spoke→hub cluster-admin)
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H'}

cvssV3_1

{'score': 9.9, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'}

Type Values Removed Values Added
CPEs cpe:/a:redhat:multicluster_engine:2.10::el9
cpe:/a:redhat:multicluster_engine:2.6::el9
cpe:/a:redhat:multicluster_engine:2.8::el9
cpe:/a:redhat:multicluster_engine:2.9::el9
References
Type Values Removed Values Added
CPEs cpe:/a:redhat:multicluster_engine:2.17::el9
References
Type Values Removed Values Added
CPEs cpe:/a:redhat:multicluster_engine cpe:/a:redhat:multicluster_engine:2.11::el9
References
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A flaw was found in the managedcluster-import-controller. The Certificate Signing Request (CSR) auto-approval logic improperly validates incoming CSRs, specifically by not inspecting the signer name or decoding the PEM-encoded x509 CSR. This vulnerability allows a privileged service account on a spoke cluster to submit a malicious CSR. Successful exploitation can lead to privilege escalation, enabling the attacker to obtain administrative credentials on the hub cluster.
Title Managedcluster-import-controller: managedcluster-import-controller: csr auto-approver does not validate certificate subject, signername, or requester identity
First Time appeared Redhat
Redhat multicluster Engine
Weaknesses CWE-295
CPEs cpe:/a:redhat:multicluster_engine
Vendors & Products Redhat
Redhat multicluster Engine
References
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Sep 29, 2026, 7:41 PM
Reserved
Jul 27, 2026, 5:51 PM
Status
Awaiting Analysis
Published
Aug 17, 2026, 9:16 PM
Modified
Sep 29, 2026, 8:17 PM
Severity
Important
Public date
Aug 17, 2026, 8:29 PM