Argo Workflows 3.6.5 through 4.0.4 contain an unchecked array index in the pod informer's podGCFromPod() function, which can be triggered by a malformed workflows.argoproj.io/pod-gc-strategy annotation on a workflow pod. When this occurs, the controller goroutine panics outside its recover scope, causing the entire Argo Workflows controller process to crash. The poisoned pod remains across restarts, leading to a crash loop that stops all workflow processing and effectively denies service to users of the workflow engine. The weakness is reflected in CWE‑129 and CWE‑1285, unchecked indexing and array bounds errors.

The affected product is Argo Workflows from the argoproj organization. Versions from 3.6.5 up to and including 4.0.4 are impacted. The vulnerability is fixed in releases 4.0.5 and 3.7.14, which should be applied by users on the affected versions.

The CVSS score of 7.7 indicates a fairly high severity, while the EPSS score of under 1% shows a low probability of exploitation under current conditions. The vulnerability is not catalogued by CISA in KEV. Based on the description, the likely attack vector requires an adversary who can submit or modify workflow pods within the Kubernetes cluster, inserting a malformed workflows.argoproj.io/pod-gc-strategy annotation. This suggests a local or privileged cluster attacker would need sufficient permissions to create or alter workflow pods to exploit the flaw.