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

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Summary

CVECVE-2026-56743
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-15 20:17:51 UTC
Updated2026-07-17 17:29:02 UTC
DescriptionCilium 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.

Risk And Classification

Primary CVSS: v3.1 5.4 MEDIUM from [email protected]

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

EPSS: 0.001580000 probability, percentile 0.054140000 (date 2026-07-17)

Problem Types: CWE-863 | CWE-863 CWE-863: Incorrect Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.4MEDIUMCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
3.1CNADECLARED5.4MEDIUMCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Cilium Cilium All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Cilium Cilium affected >= 1.19.0, < 1.19.5 Not specified

References

ReferenceSourceLinkTags
github.com/cilium/cilium/commit/bacea640404c0805c23515353dc1681c5bf35171 [email protected] github.com Patch
github.com/cilium/cilium/releases/tag/v1.19.5 [email protected] github.com Release Notes
github.com/cilium/cilium/pull/46456 [email protected] github.com Patch
github.com/cilium/cilium/commit/1c84ae3b58a7cd54f7ee355e6c524c82f620eae8 [email protected] github.com Patch
github.com/cilium/cilium/pull/46305 [email protected] github.com Patch
github.com/cilium/cilium/security/advisories/GHSA-fm8w-2m5w-9j7r [email protected] github.com Vendor Advisory
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