GHSA-hxv8-4j4r-cqgv BIT-cilium-2026-33726 BIT-cilium-operator-2026-33726 BIT-hubble-relay-2026-33726 CVE-2026-33726 GO-2026-4856

Cilium L7 proxy may bypass Kubernetes NetworkPolicy for same-node traffic

Medium Go

Severity: 5.4 / 10; Medium · CVSS 3.1
Exploit chance (EPSS): 0.26%; Chance of exploitation in the next 30 days. Higher than 17.28% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-284 Improper Access Control; CWE-863 Incorrect Authorization
Fix: 1.17.14; Upgrade github.com/cilium/cilium to this version or later

Description

Impact

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.

Patches

This issue was fixed by #44693.

This issue affects:

Cilium v1.19 between v1.19.0 and v1.19.1 inclusive
Cilium v1.18 between v1.18.0 and v1.18.7 inclusive
All versions of Cilium prior to v1.17.13

This issue is fixed in:

Cilium v1.19.2
Cilium v1.18.8
Cilium v1.17.14

Workarounds

Disclaimer: 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.

Acknowledgements

The Cilium community has worked together with members of the Northflank and Isovalent teams to prepare these mitigations. Cilium thanks @sudeephb and @Champ-Goblem for reporting the issue and to @smagnani96 and @julianwiedmann for helping with the resolution.

For more information

Anyone who believes a vulnerability affecting Cilium has been found is strongly encouraged to report it to the security mailing list at security@cilium.io. This is a private mailing list for the Cilium security team, and any such report will be treated as top priority. Please also address any comments or questions on this advisory to the same mailing list.

Affected versions

Go

Package	Vulnerable	Fixed in
github.com/cilium/cilium	`< 1.17.14`	`1.17.14`
github.com/cilium/cilium	`>= 1.18.0, < 1.18.8`	`1.18.8`
github.com/cilium/cilium	`>= 1.19.0, < 1.19.2`	`1.19.2`
github.com/cilium/cilium	`< 1.17.14` `>= 1.18.0, < 1.18.8` `>= 1.19.0, < 1.19.2`	`1.17.14` `1.18.8` `1.19.2`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

github.com/cilium/cilium Go → `1.17.14`

go

go get github.com/cilium/cilium@v1.17.14 && go mod tidy

Severity breakdown

CVSS 3.1 5.4

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

Attack vector: Adjacent
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

Weakness

CWE-284: Improper Access Control

The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

How to prevent it

Architecture and Design, Operation: Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
Architecture and Design: Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

CWE-863: Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

How to prevent it

Architecture and Design: Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
Architecture and Design: Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor [REF-7].
Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
Architecture and Design: For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page. One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.
System Configuration, Installation: Use the access control capabilities of your operating system and server environment and define your access control lists accordingly. Use a "default deny" policy when defining these ACLs.

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2026-33726

Packages

github.com/cilium/cilium

Timeline

Mar 26, 2026 Published
Sep 10, 2026 Last updated by the source
Nov 1, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-fm8w-2m5w-9j7r Cilium may unexpectedly allow ingress traffic from the local namespace when a Kubernetes NetworkPolicy is configured with an ipBlock match	Medium	Also affects github.com/cilium/cilium
GHSA-w7c2-w76w-5hmj Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces	High	Also affects github.com/cilium/cilium
GHSA-q6h5-q3q6-f87x CiliumLocalRedirectPolicy addressMatcher allows cross-namespace service traffic hijacking and can break service translation	Medium	Also affects github.com/cilium/cilium
GHSA-3fcv-jvfp-m4q9 Cilium vulnerable to sensitive information disclosure and cluster disruption via local Envoy admin socket access	High	Also affects github.com/cilium/cilium
GHSA-gj49-89wh-h4gj Cillium exposes sensitive information included in the cilium-bugtool debug archive	Medium	Also affects github.com/cilium/cilium
GHSA-5r23-prx4-mqg3 Cilium may not enforce host firewall policies when Native Routing, WireGuard and Node Encryption are enabled	Medium	Also affects github.com/cilium/cilium
GHSA-38pp-6gcp-rqvm Cilium with misconfigured toGroups in policies can lead to unrestricted egress traffic	Medium	Also affects github.com/cilium/cilium
GHSA-5vxx-c285-pcq4 In Cilium, packets from terminating endpoints may not be encrypted in Wireguard-enabled clusters	Medium	Also affects github.com/cilium/cilium

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