medium5.4
CVE-2026-56743
Cilium may unexpectedly allow ingress traffic from the local namespace when a Kubernetes NetworkPolicy is configured with an ipBlock match
Impact
Cilium is a networking, observability, and security solution. From 1.19.0 to 1.19.4, standard Kubernetes NetworkPolicy specifications using CIDR-based ipBlock rules without pod or namespace selectors erroneously generate a wildcard namespace allow rule when Cilium is configured with a custom clusterName rather than the default any value. The parser incorrectly instantiates a pod selector on selectorless peer definitions, allowing traffic from other workloads in the same namespace as the subject of the policy. This issue is fixed in version 1.19.5.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/cilium/cilium | >= 1.19.0, < 1.19.5 | 1.19.5 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Cilium | Cilium | from 1.19.0 before 1.19.5 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-fm8w-2m5w-9j7r
- https://github.com/cilium/cilium/security/advisories/GHSA-fm8w-2m5w-9j7r
- https://nvd.nist.gov/vuln/detail/CVE-2026-56743
- https://github.com/cilium/cilium/pull/46305
- https://github.com/cilium/cilium/pull/46456
- https://github.com/cilium/cilium/commit/1c84ae3b58a7cd54f7ee355e6c524c82f620eae8
- https://github.com/cilium/cilium/commit/bacea640404c0805c23515353dc1681c5bf35171
- https://github.com/cilium/cilium/releases/tag/v1.19.5