CVE-2023-27594: Potential network policy bypass when routing IPv6 traffic in github.com/cilium/cilium
Summary
CVE-2023-27594: Potential network policy bypass when routing IPv6 traffic. Affects github.com/cilium/cilium across 3 version ranges.
< 1.11.15
>= 1.12.0, < 1.12.8
>= 1.13.0, < 1.13.1
Fixed in 1.11.15, 1.12.8 or 1.13.1, depending on the release line you run. How to fix ↓
Also tracked for
- hubble-ui-backend · Bitnami
- hubble-ui · Bitnami
- cilium-proxy · Bitnami
- hubble · Bitnami
- hubble-relay · Bitnami
- cilium · Bitnami
- cilium-operator · Bitnami
The same CVE-2023-27594 is tracked separately for each ecosystem and vendor. Its fix information is the same; the package and affected versions differ.
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Background
github.com/cilium/cilium is an open-source project written in Go that provides networking and security capabilities for containerized applications in Kubernetes environments. It is responsible for routing traffic and enforcing network policies within the cluster. Cilium supports both IPv4 and IPv6 traffic, but IPv6 is disabled by default. The vulnerability in question affects the routing of IPv6 traffic when certain conditions are met.
Vulnerability Detail
Under specific conditions, Cilium may misattribute the source IP address of IPv6 traffic to a cluster, incorrectly identifying external traffic as originating from the host running Cilium. This misattribution can lead to the bypassing of network policies for that cluster, depending on the specific policies in place. It is important to note that this vulnerability only affects IPv6 traffic and is not present when using Cilium's kube-proxy replacement feature. The vulnerability has a CVSS score of 4.2.
How To Fix
Latest published version: v1.20.3 as of 22 Oct 2026
go get github.com/cilium/cilium@v1.20.3Upgrading to it may include breaking changes; the versions below are the minimum fixed release for this vulnerability.
If you can't move to the latest
The minimum fixed version depends on the release line you run.
-
< 1.11.151.11.15go get github.com/cilium/cilium@v1.11.15 -
>= 1.12.0, < 1.12.81.12.8go get github.com/cilium/cilium@v1.12.8 -
>= 1.13.0, < 1.13.11.13.1go get github.com/cilium/cilium@v1.13.1
Tip — Not sure which release line you're on? Vulert can find the fix for the version you are using. Scan free →
Workaround
If updating Cilium is not immediately feasible, a workaround is to disable IPv6 routing. Since IPv6 is disabled by default, this workaround may already be in place for many installations.
Conclusion
The vulnerability in github.com/cilium/cilium allows for potential network policy bypass when routing IPv6 traffic. Users are advised to update to the fixed versions of Cilium or disable IPv6 routing as a workaround. For further assistance with vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for github.com/cilium/cilium →
FAQ
The vulnerability allows external traffic to be misattributed to a cluster, potentially bypassing network policies and compromising security measures.
Versions prior to 1.11.15, 1.12.8, and 1.13.1 are affected by this vulnerability.
No, this vulnerability only affects IPv6 traffic.
No, the kube-proxy replacement feature in Cilium is not affected by this vulnerability.
The Cilium community, in collaboration with members of Isovalent, discovered and fixed this vulnerability. Special thanks to Yusuke Suzuki for identifying and resolving the issue.
Related vulnerabilities
Recent vulnerabilities recorded for github.com/cilium/cilium.
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