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Fencer Vulns
high 8.7

CVE-2026-66785 json

Submariner: submariner: missing validation of remote endpoint subnets and clusterid enables cross-cluster traffic hijack

published 2026-08-20 2 mo ago modified 2026-10-19 20 d ago also EUVD-2026-63572

cvss
8.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

Summary

A flaw was found in Submariner. This vulnerability allows a malicious cluster (spoke) to redirect network traffic from other connected clusters (peer clusters) by publishing a specially crafted network endpoint. The system fails to properly validate the network subnets provided by the malicious cluster, enabling it to declare arbitrary network ranges. Consequently, all network traffic intended for these arbitrary ranges from peer clusters will be rerouted through the attacker's tunnel, potentially leading to unauthorized information disclosure or network disruption.

Patch / fix

  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2.16 1790670231, 1790670233, 1790670243, 1790670254, 1790670439, 1790670508, 1790670912
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2.17 1788023916, 1788023940, 1788043961, 1788043964, 1788043970, 1788073481, 1788105072

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-2026-66785 updated cvss 8.7

submariner: submariner: missing validation of remote Endpoint subnets and ClusterID enables cross-cluster traffic hijack

  • Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/submariner-addon-rhel9, rhacm2/submariner-operator-bundle
    affected: workaround, no fix available
  • Red Hat Advanced Cluster Management for Kubernetes 2.16 rhacm2/subctl-rhel9 1790670243, rhacm2/lighthouse-agent-rhel9 1790670439, rhacm2/lighthouse-coredns-rhel9 1790670231, rhacm2/submariner-gateway-rhel9 1790670508, rhacm2/submariner-rhel9-operator 1790670912, rhacm2/submariner-globalnet-rhel9 1790670233, +1 more
    fixed: vendor fix RHSA-2026:85227
  • Red Hat Advanced Cluster Management for Kubernetes 2.17 rhacm2/subctl-rhel9 1788105072, rhacm2/lighthouse-agent-rhel9 1788023916, rhacm2/lighthouse-coredns-rhel9 1788023940, rhacm2/submariner-gateway-rhel9 1788043964, rhacm2/submariner-rhel9-operator 1788073481, rhacm2/submariner-globalnet-rhel9 1788043961, +1 more
    fixed: vendor fix RHSA-2026:63016
  • Red Hat Advanced Cluster Management for Kubernetes 2.16 rhacm2/nettest-rhel9 1790702141, rhacm2/submariner-operator-bundle 1790750775 Red Hat Advanced Cluster Management for Kubernetes 2.17 rhacm2/nettest-rhel9 1788166791, rhacm2/submariner-operator-bundle 1788217593
    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

0.21% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.7 CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N

Affected products

  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2.16
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2.17
  • Red Hat Red Hat Advanced Cluster Management for Kubernetes 2

Classification

Weakness
  • CWE-345 Insufficient Verification of Data Authenticity

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.