CVE-2026-33726
MEDIUMCilium L7 proxy may bypass Kubernetes NetworkPolicy for same-node traffic
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
github.com/cilium/cilium🐹github.com/cilium/cilium🐹github.com/cilium/ciliumReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/cilium/cilium | all versions | 1.17.14 |
| 🐹Go | github.com/cilium/cilium | ≥ 1.18.0&&< 1.18.8 | 1.18.8 |
| 🐹Go | github.com/cilium/cilium | ≥ 1.19.0&&< 1.19.2 | 1.19.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/cilium/cilium. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/cilium/cilium to 1.17.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33726 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-33726 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-33726. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-33726 in your dependencies?
O3 detects CVE-2026-33726 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.