This document provides immediate mitigation steps for CVE-2026-31431. While waiting for patched node images to roll out, you can protect your clusters using the following methods.

For GKE Standard nodes running Container-Optimized OS, you can set the initcall_blacklist=algif_aead_init kernel parameter on your nodes to disable the impacted functionality.

You can apply the privileged DaemonSet (cos-disable-algif-aead.yaml) provided in this directory to set this kernel parameter. Be mindful that this tool immediately reboots nodes; you can use the cloud.google.com/gke-algif-aead-disabled node label to control the application of the DaemonSet. This option will block legitimate usage of this kernel behavior as well as malicious usage.

Deployment Instructions:

1. Label your target nodes to control the rollout:

kubectl label nodes <node-name> cloud.google.com/gke-algif-aead-disabled=true

2. Apply the DaemonSet:

kubectl apply -f cos-disable-algif-aead.yaml

• Secure Boot: This mitigation does not work if Secure Boot is enabled. The init container will never finish initializing because Secure Boot prevents changes to the kernel command line boot options.
• Spot Nodes: We've received reports that this mitigation is intermittently failing on Spot (Preemptible VM) nodes due to cgroup configuration errors during container initialization, however we have been unable to reproduce this.
• Node Reboots: Applying this DaemonSet will immediately reboot the affected nodes.

For GKE Standard nodes running Ubuntu, you can blacklist the algif_aead module on your nodes (for example, by using a privileged DaemonSet) with the following commands:

echo "install algif_aead /bin/false" > /etc/modprobe.d/disable-algif-aead.conf
rmmod algif_aead 2>/dev/null

GKE Autopilot does not allow running privileged daemonsets, and therefore must be mitigated by applying a custom seccomp profile to your workloads to block AF_ALG socket creation. This also works as an alternative mitigation method for GKE Standard clusters.

Note: We do not recommend relying on containers as a strict security boundary. For stronger isolation, consider using GKE Sandbox, network policies and the guidance found at https://docs.cloud.google.com/kubernetes-engine/docs/how-to/hardening-your-cluster.