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TI-2026-21448 Aliases CVE-2026-26963GHSA-5r23-prx4-mqg3

Cilium may not enforce host firewall policies when Native Routing, WireGuard and Node Encryption are enabled

Priority LOW 26CWE-863Published · Updated

Key facts

Attack vector
Adjacent network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
Low · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-863.

Summary

Cilium is a networking, observability, and security solution with an eBPF-based dataplane. Versions 1.18.0 through 1.18.5 will incorrectly permit traffic from Pods on other nodes when Native Routing, WireGuard and Node Encryption are enabled. This issue has been fixed in version 1.18.6.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0014 3rd percentileScored 2026-11-07
Fix Fixed cilium (cilium): 1.18.6github.com/cilium/cilium (Go): 1.18.6

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ciliumcilium1.18.0 to before 1.18.61.18.6Patch availableCNA
—github.com/cilium/cilium (Go)1.18.0 to before 1.18.61.18.6Patch availableGHSA-5r23-prx4-mqg3
  • cilium Vendorcilium Affected 1.18.0 to before 1.18.6 Fixed in 1.18.6 Patch available CNA
  • github.com/cilium/cilium (Go) Vendor— Affected 1.18.0 to before 1.18.6 Fixed in 1.18.6 Patch available GHSA-5r23-prx4-mqg3

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:cilium:cilium:*:*:*:*:*:*:*:*1.18.0 to before 1.18.6Vulnerablecilium
  • cpe:2.3:a:cilium:cilium:*:*:*:*:*:*:*:* Versions 1.18.0 to before 1.18.6 Vulnerable ·cilium

Remediation

  • Fix · CNA cilium (cilium) Fixed in 1.18.6
  • Fix · GHSA-5r23-prx4-mqg3 github.com/cilium/cilium (Go) Fixed in 1.18.6 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Not affected: 12 products
  • Confidential Compute Attestation
  • Multicluster Global Hub
  • Network Observability Operator
  • OpenShift Developer Tools and Services
  • OpenShift Service Mesh 2
  • Red Hat Advanced Cluster Management for Kubernetes 2
  • Red Hat Enterprise Linux 10
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • Red Hat OpenShift Container Platform 4
  • Red Hat OpenShift Virtualization 4
  • Red Hat OpenShift for Windows Containers

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-26963
  2. 2026-10-03 Alias added: GHSA-5r23-prx4-mqg3

References

Patch 2

Advisory 1

Other 3

  • TI-2024-32092 CIDR deny policies may not take effect when a more narrow CIDR allow is present CVSS 3.1HIGH 8.7
  • TI-2023-12305 Cilium eBPF filters may be temporarily removed during agent restart CVSS 3.1CRITICAL 9.8
  • TI-2023-20486 Cilium NetworkPolicy bypass via pod labels CVSS 3.1CRITICAL 9.0
  • TI-2022-11721 Incorrect Default Permissions in Cilium CVSS 3.1HIGH 8.8
  • TI-2026-36600 Cilium: Sensitive information disclosure and cluster disruption via local Envoy admin socket access CVSS 3.1CRITICAL 9.2
  • TI-2026-40915 Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces CVSS 3.1HIGH 8.9
See all 34 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences