Vulnerability in Red Hat Multicluster Engine For Kubernetes
CVE-2026-66795
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.
Vulnerability class: Improper Certificate Validation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.9 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (39.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 39.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
Weakness classification (CWE)
References
- access.redhat.com/security/cve/CVE-2026-66795 (vdb-entry)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking)
- access.redhat.com/errata/RHSA-2026:59556 (vendor-advisory)
- access.redhat.com/errata/RHSA-2026:59593 (vendor-advisory)
- access.redhat.com/errata/RHSA-2026:59557 (vendor-advisory)
- access.redhat.com/errata/RHSA-2026:59558 (vendor-advisory)
- access.redhat.com/errata/RHSA-2026:59559 (vendor-advisory)
- access.redhat.com/errata/RHSA-2026:59579 (vendor-advisory)
Frequently asked questions
- What is CVE-2026-66795?
- CVE-2026-66795 is a critical-severity vulnerability in Red Hat Multicluster Engine For Kubernetes, classified under Improper Certificate Validation. CVSS score: 9.9/10. Published 2026-08-17.
- How severe is CVE-2026-66795?
- Critical severity. CVSS v3 base score is 9.9 out of 10.