Skip to content
Fencer Vulns
critical 9.9

CVE-2026-66795 json

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

published 2026-08-17 2 mo ago modified 2026-09-29 40 d ago also EUVD-2026-60452

cvss
9.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

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.

Patch / fix

  • Red Hat multicluster engine for Kubernetes 2.10 1787078272
  • Red Hat multicluster engine for Kubernetes 2.11 1787078330
  • Red Hat multicluster engine for Kubernetes 2.17 1786577915
  • Red Hat multicluster engine for Kubernetes 2.6 1787260779
  • Red Hat multicluster engine for Kubernetes 2.8 1787259044
  • Red Hat multicluster engine for Kubernetes 2.9 1787078307

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-66795 updated cvss 9.9

managedcluster-import-controller: CSR auto-approver does not validate certificate Subject or signerName (spoke→hub cluster-admin)

  • Red Hat multicluster engine for Kubernetes 2.6 multicluster-engine/managedcluster-import-controller-rhel9 1787260779
    fixed: vendor fix RHSA-2026:59579
  • Red Hat multicluster engine for Kubernetes 2.8 multicluster-engine/managedcluster-import-controller-rhel9 1787259044
    fixed: vendor fix RHSA-2026:59558
  • Red Hat multicluster engine for Kubernetes 2.9 multicluster-engine/managedcluster-import-controller-rhel9 1787078307
    fixed: vendor fix RHSA-2026:59559
  • Red Hat multicluster engine for Kubernetes 2.10 multicluster-engine/managedcluster-import-controller-rhel9 1787078272
    fixed: vendor fix RHSA-2026:59557
  • Red Hat multicluster engine for Kubernetes 2.11 multicluster-engine/managedcluster-import-controller-rhel9 1787078330
    fixed: vendor fix RHSA-2026:59556
  • Red Hat multicluster engine for Kubernetes 2.17 multicluster-engine/managedcluster-import-controller-rhel9 1786577915
    fixed: vendor fix RHSA-2026:59593
  • Red Hat multicluster engine for Kubernetes 2.6 multicluster-engine/hive-rhel9 1787291123, multicluster-engine/work-rhel9 1787263188, multicluster-engine/discovery-rhel9 1787263531, multicluster-engine/placement-rhel9 1787260699, multicluster-engine/console-mce-rhel9 1787264250, multicluster-engine/must-gather-rhel9 1787264198, +20 more Red Hat multicluster engine for Kubernetes 2.8 multicluster-engine/hive-rhel9 1787291250, multicluster-engine/work-rhel9 1787259113, multicluster-engine/discovery-rhel9 1787259074, multicluster-engine/placement-rhel9 1787259108, multicluster-engine/console-mce-rhel9 1787259048, multicluster-engine/must-gather-rhel9 1787258992, +20 more Red Hat multicluster engine for Kubernetes 2.9 multicluster-engine/hive-rhel9 1787205132, multicluster-engine/work-rhel9 1786933545, multicluster-engine/discovery-rhel9 1786658519, multicluster-engine/placement-rhel9 1786491555, multicluster-engine/console-mce-rhel9 1787079359, multicluster-engine/must-gather-rhel9 1786837240, +23 more Red Hat multicluster engine for Kubernetes 2.10 multicluster-engine/hive-rhel9 1787205371, multicluster-engine/work-rhel9 1786933256, multicluster-engine/discovery-rhel9 1787071404, multicluster-engine/placement-rhel9 1786548467, multicluster-engine/console-mce-rhel9 1787079364, multicluster-engine/must-gather-rhel9 1786548899, +24 more Red Hat multicluster engine for Kubernetes 2.11 multicluster-engine/hive-rhel9 1787291933, multicluster-engine/work-rhel9 1786907276, multicluster-engine/discovery-rhel9 1786911975, multicluster-engine/placement-rhel9 1786911984, multicluster-engine/console-mce-rhel9 1787065052, multicluster-engine/must-gather-rhel9 1786911926, +25 more Red Hat multicluster engine for Kubernetes 2.17 multicluster-engine/hive-rhel9 1787033495, multicluster-engine/work-rhel9 1786933423, multicluster-engine/maestro-rhel9 1786985023, multicluster-engine/discovery-rhel9 1786681989, multicluster-engine/placement-rhel9 1786983381, multicluster-engine/console-mce-rhel9 1786668856, +28 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
2 mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Affected products

  • Red Hat multicluster engine for Kubernetes 2.10
  • Red Hat multicluster engine for Kubernetes 2.11
  • Red Hat multicluster engine for Kubernetes 2.17
  • Red Hat multicluster engine for Kubernetes 2.6
  • Red Hat multicluster engine for Kubernetes 2.8
  • Red Hat multicluster engine for Kubernetes 2.9

Classification

Weakness
  • CWE-295 Improper Certificate Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.