How severe is CVE-2026-33726?

CVE-2026-33726 has a CVSS score of 5.4/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-33726?

CVE-2026-33726 affects the following packages: github.com/cilium/cilium (Go), github.com/cilium/cilium (Go), github.com/cilium/cilium (Go). Ecosystems affected: Go.

How do I fix CVE-2026-33726?

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.

How do I detect CVE-2026-33726 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/cilium/cilium, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-33726 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2026-33726 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-33726 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-33726?

CVE-2026-33726 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 17th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-33726?

CVE-2026-33726 is classified as CWE-284 (CWE-284), CWE-863 (CWE-863). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-33726 published, and has it been updated?

CVE-2026-33726 was published on March 27, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

MEDIUM severity

CVE-2026-33726 — cilium

MEDIUMFix: cilium/cilium#44693

CVE-2026-33726 is a medium-severity (CVSS 5.4) CWE-284 vulnerability in github.com/cilium/cilium. A fix is available for github.com/cilium/cilium — see the affected versions and patch details below.

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

Also known asBIT-cilium-2026-33726BIT-cilium-operator-2026-33726BIT-hubble-relay-2026-33726GHSA-hxv8-4j4r-cqgvGO-2026-4856

Published

Mar 27, 2026

Updated

Oct 28, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-33726.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs17th percentile — riskier than 17% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

3 pkgs affected

🐹github.com/cilium/cilium🐹github.com/cilium/cilium🐹github.com/cilium/cilium

Real-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

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 [email protected]. 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 Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/cilium/cilium`	all versions	1.17.14`go get github.com/cilium/cilium@v1.17.14`
🐹Go	`github.com/cilium/cilium`	≥ 1.18.0&&< 1.18.8	1.18.8`go get github.com/cilium/cilium@v1.18.8`
🐹Go	`github.com/cilium/cilium`	≥ 1.19.0&&< 1.19.2	1.19.2`go get github.com/cilium/cilium@v1.19.2`

Affected Products

1 product · 3 configurations

Application

ciliumcilium

≥ 1.19.0 && < 1.19.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/cilium/cilium, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### Impact Ingress [Network Policies](https://docs.cilium.io/en/stable/network/kubernetes/policy/#network-policy) are not enforced for traffic from pods to L7 Services ([Envoy](https://docs.cilium.io/en/stable/network/servicemesh/l7-traffic-management), GAMMA) with a local backend on the same node, when [Per-Endpoint Routing](https://docs.cilium.io/en/stable/network/concepts/routing/#routing) is enabled and [BPF Host Routing](https://docs.cilium.io/en/stable/operations/performance/tuning/#ebpf-host-routing) is disabled. Per-Endpoint Routing is disabled by default, but is automatically enable