CVE-2026-26963 Cilium may not enforce host firewall policies when Native Routing, WireGuard and Node Encryption are enabled
Attackers can bypass host firewall policies in Cilium when specific encryption and routing features are enabled, allowing unauthorized cross-node traffic.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-26963?
CVE-2026-26963 is a medium-severity missing authorization vulnerability in cilium, published on 19 Feb 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Cilium is a networking, observability, and security solution with an eBPF-based dataplane. Versions 1.18.0 through 1.18.5 will incorrectly permit traffic from Pods on other nodes when Native Routing, WireGuard and Node Encryption are enabled. This issue has been fixed in version 1.18.6.
Weakness: CWE-863
Which versions are affected by CVE-2026-26963?
6 open source packages ship an affected version, including github.com/cilium/cilium, cilium and cilium-operator. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/cilium/cilium Go | From 1.18.0 | 1.18.6 |
github.com/cilium/cilium Go | From 1.18.0 | 1.18.6 |
github.com/cilium/cilium Go | From 1.18.0 | 1.18.6 |
cilium Bitnami | From 1.18.0 | 1.18.6 |
cilium-operator Bitnami | From 1.18.0 | 1.18.6 |
hubble-relay Bitnami | From 1.18.0 | 1.18.6 |
Products include Cilium Cilium.
How do I fix CVE-2026-26963?
Upgrade github.com/cilium/cilium to 1.18.6 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-26963 being exploited?
There is no known exploitation of CVE-2026-26963 in the wild and no public exploit code.
Other vulnerabilities in cilium
- CVE-2026-49445 Cilium: Sensitive information disclosure and cluster disruption via local Envoy admin socket access
- CVE-2022-29178 Incorrect Default Permissions in Cilium
- CVE-2024-28860 Insecure IPsec transport encryption in Cilium
- CVE-2026-41520 Cillium exposes sensitive information included in the cilium-bugtool debug archive
- CVE-2024-37307 Cilium leaks sensitive information in cilium-bugtool
Sources
Also known as BIT-cilium-2026-26963, BIT-cilium-operator-2026-26963, BIT-hubble-relay-2026-26963, GHSA-5r23-prx4-mqg3, GO-2026-4522, MINI-92x6-8jwj-p6mq and 4 more.