Cases46 cases

6 to 10 of 46

1. IL-0247 One in a million search requests took 100 times longer on Pinterest's Manas leaf nodes after moving to Kubernetes

   Pinterest2025

   Symptoms

   During performance testing of Pinterest's search system Manas on its new Kubernetes platform, a small but persistent share of search requests timed out. About one request in a million took 100 times longer than usual.

   High latencyIntermittent timeouts

   Root cause

   Software defect

   Component

   Telemetry agentLinux kernel

   Contributing factor

   Unreviewed defaults

   Detection

   Performance testing with traffic sent to a test cluster showed a small but persistent percentage of requests timing out.

   Remediation

   • Disabled cAdvisor's working set size estimation on all PinCompute nodes

   Lessons

   CPU shielding does not fully isolate a process from its neighbours. Showing early that the node image was not the cause narrowed the search and avoided dead ends. Simple blackbox debugging, breaking things until the system stops working, works as a way of bisecting the problem.

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2. IL-0078 Enabling EKS secrets encryption with KMS through Terraform removed worker node IAM permissions and took down all ZenML Pro workspaces

   ZenML2025

   Symptoms

   Between 12 AM and 8 AM CEST on 11 May 2025, every ZenML Pro workspace server was unreachable, so customers could not use workspace UIs or pipelines. The ZenML Pro dashboard was not affected.

   Service outage

   Trigger

   At 23:38 on 10 May, secrets encryption with AWS KMS was enabled through Terraform as part of the EKS module upgrade.

   Root cause

   Software defect

   Component

   TerraformNode pool

   Contributing factor

   Unrepresentative stagingDeferred upgrades

   Detection

   Engineers found the cluster degraded when they resumed the upgrade at 06:00.

   Remediation

   • deleted and recreated the EKS node group with the correct IAM permissions and configuration
   • restored service access across all affected ZenML Pro environments

   Action items

   • Upgrade all Terraform modules (EKS, VPC) to current supported versions
   • Complete the EKS cluster upgrades as planned
   • Review the strategy for periodic Kubernetes and infrastructure upgrades to prevent a recurrence

   Lessons

   A successful upgrade on a much smaller staging cluster understated the risk of the same change in production. Skipping Kubernetes and module versions let upgrade complexity build up until one upgrade carried many changes at once.

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3. IL-0053 Unauthenticated ingress-nginx admission webhook let anyone on the pod network run code and read every Secret in the cluster (IngressNightmare, CVE-2025-1974)

   Wiz2025

   Symptoms

   This is a vulnerability report, not an outage, so nothing failed visibly. A cluster is exposed if it runs Ingress NGINX Controller older than 1.12.1 or 1.11.5 with its validating admission webhook enabled. Wiz suggests `kubectl get pods --all-namespaces --selector app.kubernetes.io/name=ingress-nginx` to find it. The webhook accepts AdmissionReview requests over HTTP without authentication from any pod, and Wiz found more than 6,500 clusters exposing it to the public internet.

   Unauthorised access or a foreign workload

   Trigger

   Wiz Research reviewed the code of the Ingress NGINX admission controller and reported the first findings to Kubernetes on 31 December 2024.

   Root cause

   Software defect

   Component

   Ingress controllerAdmission webhook

   Contributing factor

   Unreviewed defaultsExcessive blast radius

   Detection

   Found by Wiz Research in a code review of the admission controller, not by an operator.

   Remediation

   • Kubernetes patched the injection flaws CVE-2025-1097, CVE-2025-1098 and CVE-2025-24514
   • Kubernetes removed NGINX configuration testing from the ingress-nginx admission controller, resolving CVE-2025-1974
   • released Ingress NGINX Controller 1.12.1 and 1.11.5

   Lessons

   Admission webhooks often run as web servers inside the cluster without authentication and with relatively high privileges, so any pod can reach them, and the flaws pair well with SSRF in an application. Wiz concludes that `nginx -t` should be considered harmful when it processes unsanitized user input. Wiz recommends upgrading, keeping the webhook off the internet and allowing only the API server to reach it with network policies. If upgrading must wait, disable the webhook (Helm: controller.admissionWebhooks.enabled=false; manual installs: delete the ValidatingWebhookConfiguration ingress-nginx-admission and remove --validating-webhook from the controller) and enable it again after the upgrade.

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4. IL-0233 A VPC control plane release broke IP alias routes in Nebius eu-west1, and Managed Kubernetes pods lost connectivity

   Nebius2025

   Symptoms

   On 13 March 2025 practically every pod of Nebius Managed Services for Kubernetes in the eu-west1 region lost network connectivity for at least some time between 13:36 and 18:11 UTC. Packets for the affected IP alias routes were not processed by the data plane. The eu-north1 region was not affected.

   Network unreachable

   Trigger

   A release of a VPC control plane component in eu-west1, deployed to canaries from 13:36 UTC and to all other nodes from 14:35 UTC, changed route distinguisher values for a new feature. The change made a long-standing bug in the handling of route announcements take effect for the update messages of Managed Kubernetes pods.

   Root cause

   Software defect

   Component

   Network control plane (SDN)BGP routing

   Contributing factor

   Ineffective rollbackGap in automated testsMonitoring blind spot

   Remediation

   • Restarted the host VPC component on the affected nodes one node at a time
   • Restarted the host VPC component on the remaining nodes in parallel once the restart was known to fix the problem

   Action items

   • Fix the bug in the VPC host component itself
   • Add an alert on a diverging number of routes
   • Add an alert on the number of drops in the data plane
   • Develop a way to reset endpoints without restarting the host VPC component
   • Move the VPC's persistent e2e test virtual machines to canary hosts
   • Add persistent e2e tests for Managed Services for Kubernetes
   • Run e2e tests more often
   • Add a deployment stage in which non-critical internal services receive updates first

   Lessons

   The failure needed both an existing IP alias at release time and a particular order of node updates, and neither the testing installation nor the canaries met both, so neither caught it. Missing alerts on technical metrics that deviate from normal, here the number of routes and the number of drops, made the response much slower.

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5. IL-0081 API requests timed out during deployment rollouts because the ingress-nginx enable-serial-reloads option held back endpoint updates while a long NGINX reload was running

   Cresta2025

   Symptoms

   During a deployment, traffic into the Kubernetes cluster started hitting dead ends: some API requests timed out and requests were slow and disrupted while the rollout ran.

   Intermittent timeoutsStale endpoint routingHigh latency

   Trigger

   A deployment rollout changed backend endpoints while a long-running NGINX full reload was in progress, with the enable-serial-reloads option enabled on the ingress-nginx controller.

   Root cause

   Software defect

   Component

   Ingress controller

   Contributing factor

   –

   Remediation

   • restarted the NGINX Ingress controller as an attempt to resolve the problem

   Action items

   • Open an issue in kubernetes/ingress-nginx describing how enable-serial-reloads blocks dynamic endpoint updates

   Lessons

   A flag meant only to serialise full reloads also delayed endpoint updates, which opened a window during rollouts in which the ingress routed to pods that no longer existed. Options that change how the ingress controller applies configuration need to be checked against what happens to endpoint updates during a long reload.

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