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Vulnerability · Published Jul 15, 2026 · Assigned by GitHub_M

CVE-2026-56743Cilium may unexpectedly allow ingress traffic from the local namespace when a Kubernetes NetworkPolicy is configured with an ipBlock match

Medium 5.4

In plain English

A medium-severity incorrect authorization in cilium from cilium. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 16% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.4Medium
Exploit odds (30 days)0.2%top 83.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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 & fixed versions

EcosystemPackageFixed inAdvisory
Gogithub.com/cilium/cilium1.19.5GHSA-fm8w-2m5w-9j7r
Gogithub.com/cilium/cilium1.19.5GO-2026-6367

Affected products (as reported)

VendorProductVersions
cilium cilium >= 1.19.0, < 1.19.5

Weakness: CWE-863 · Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

References