Cilium up to 1.17.13/1.18.7/1.19.1 access control

Summaryinfo

A vulnerability was found in Cilium up to 1.17.13/1.18.7/1.19.1 and classified as critical. This affects an unknown function. Executing a manipulation can lead to access control. This vulnerability is tracked as CVE-2026-33726. The attack is only possible within the local network. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Cilium up to 1.17.13/1.18.7/1.19.1 and classified as critical. This vulnerability affects an unknown code. The manipulation with an unknown input leads to a access control vulnerability. The CWE definition for the vulnerability is CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Cilium is a networking, observability, and security solution with an eBPF-based dataplane. Prior to versions 1.17.14, 1.18.8, and 1.19.2, Ingress Network Policies are not enforced for traffic from pods to L7 Services (Envoy, GAMMA) with a local backend on the same node, when Per-Endpoint Routing is enabled and BPF Host Routing is disabled. Per-Endpoint Routing is disabled by default, but is automatically enabled in deployments using cloud IPAM, including Cilium ENI on EKS (`eni.enabled`), AlibabaCloud ENI (`alibabacloud.enabled`), Azure IPAM (`azure.enabled`, but not AKS BYOCNI), and some GKE deployments (`gke.enabled`; managed offerings such as GKE Dataplane V2 may use different defaults). It is typically not enabled in tunneled deployments, and chaining deployments are not affected. In practice, Amazon EKS with Cilium ENI mode is likely the most common affected environment. Versions 1.17.14, 1.18.8, and 1.19.2 contain a patch. There is currently no officially verified or comprehensive workaround for this issue. The only option would be to disable per-endpoint routes, but this will likely cause disruptions to ongoing connections, and potential conflicts if running in cloud providers.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-33726 since 03/23/2026. The exploitation appears to be easy. The attack needs to be initiated within the local network. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1068.

Upgrading to version 1.17.14, 1.18.8 or 1.19.2 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

• Cilium

Version

• 1.17.0
• 1.17.1
• 1.17.2
• 1.17.3
• 1.17.4
• 1.17.5
• 1.17.6
• 1.17.7
• 1.17.8
• 1.17.9
• 1.17.10
• 1.17.11
• 1.17.12
• 1.17.13
• 1.18.0
• 1.18.1
• 1.18.2
• 1.18.3
• 1.18.4
• 1.18.5
• 1.18.6
• 1.18.7
• 1.19.0
• 1.19.1

Website

• Product: https://github.com/cilium/cilium/

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