Incorrect authorization in Cilium - CVE-2026-56743
Published: November 9, 2026
Vulnerability identifier: #VU162615
CSH Severity: Low
CVSS v4: 5.1 [CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-56743
CWE-ID: CWE-863
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a low-privileged adjacent-network attacker to bypass ingress restrictions and reach protected workloads from within the same namespace.
The vulnerability exists due to Cilium incorrectly adding a wildcard namespace allowance when parsing Kubernetes NetworkPolicy rules containing only an ipBlock match under a non-default clusterName configuration. A low-privileged adjacent-network attacker can send traffic from a workload in the protected workload's namespace, gaining access that the policy should restrict to the specified CIDR.
Affected software
Cilium
How to mitigate CVE-2026-56743
Install security update from vendor's website.
Cilium - update to 1.19.5