Incorrect authorization in Cilium - CVE-2026-26963
Published: November 9, 2026
Vulnerability identifier: #VU162611
CSH Severity: Medium
CVSS v4: 5.3 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-26963
CWE-ID: CWE-863
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows an unauthenticated adjacent-network attacker to bypass Cilium host firewall policies and reach hosts from Pods on other nodes.
The vulnerability exists due to incorrect host policy enforcement for inter-node Pod traffic when Native Routing, WireGuard, and Node Encryption are all enabled, a non-default configuration. An unauthenticated adjacent-network attacker can send traffic from a Pod on another node and have it incorrectly permitted despite restrictive host policies.
Affected software
Cilium
How to mitigate CVE-2026-26963
Install security update from vendor's website.
Cilium - update to 1.18.6