# CVE-2026-40886: Argo Workflows denial of service via malformed pod annotation

Source: https://junglewise.ai/threats/cve-2026-40886-argo-workflows-denial-of-service-via-malformed-pod-annotation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-23. Updated: 2026-06-30  
License: CC BY 4.0 with a link back

CVE-2026-40886 · Severity: high · CVSS 7.7 · Published 2026-04-23

Argo Workflows is an automation engine used to run complex parallel jobs on Kubernetes clusters. A vulnerability allows any user with permission to create workflows to crash the central controller by providing a malformed configuration. This results in a persistent denial-of-service where all workflow processing across the entire cluster is halted until the malicious entry is manually removed.

Technologies: [Argo Project Workflows](https://junglewise.ai/threats/technologies/workflows), [github.com/argoproj/argo-workflows (Go)](https://junglewise.ai/threats/technologies/github-com-argoproj-argo-workflows), [github.com/argoproj/argo-workflows/v2 (Go)](https://junglewise.ai/threats/technologies/github-com-argoproj-argo-workflows-v2), [github.com/argoproj/argo-workflows/v3 (Go)](https://junglewise.ai/threats/technologies/github-com-argoproj-argo-workflows-v3), [github.com/argoproj/argo-workflows/v4 (Go)](https://junglewise.ai/threats/technologies/github-com-argoproj-argo-workflows-v4). Vendors: [Argo Project](https://junglewise.ai/threats/vendors/argo-project), [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-40886 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-40886 being exploited in the wild.

**How severe is CVE-2026-40886?** High severity, with a CVSS score of 7.7, published 23 April 2026.

**Which products and versions are affected?** Argo Project Workflows >= 3.6.5, <= 3.6.19; >= 3.7.0, <= 3.7.13; >= 4.0.0, <= 4.0.4; github.com/argoproj/argo-workflows (Go) SEMVER:introduced=0; github.com/argoproj/argo-workflows/v2 (Go) SEMVER:introduced=0; github.com/argoproj/argo-workflows/v3 (Go) SEMVER:introduced=3.6.5, SEMVER:introduced=3.7.0,fixed=3.7.14; and 1 more.

**Is there a fix for CVE-2026-40886?** Yes. github.com/argoproj/argo-workflows/v3 (Go): upgrade to 3.7.14 or later; github.com/argoproj/argo-workflows/v4 (Go): upgrade to 4.0.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-40886 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-40886?** Check whether you run Argo Project Workflows, github.com/argoproj/argo-workflows (Go), github.com/argoproj/argo-workflows/v2 (Go) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/argoproj/argo-workflows/v3 (Go): upgrade to 3.7.14 or later

  ```sh
  go get github.com/argoproj/argo-workflows/v3@v3.7.14
  ```

- github.com/argoproj/argo-workflows/v4 (Go): upgrade to 4.0.5 or later

  ```sh
  go get github.com/argoproj/argo-workflows/v4@v4.0.5
  ```


## Technical details

An improper validation of an array index (CWE-129) exists in the Argo Workflows controller's pod informer. Specifically, the podGCFromPod() function splits the 'workflows.argoproj.io/pod-gc-strategy' annotation value by a forward slash and unconditionally attempts to access the second element of the resulting array. If a user submits a workflow with an annotation lacking a slash, the controller triggers an out-of-bounds panic. Because this panic occurs within an informer goroutine outside the main recovery scope, the entire controller process crashes. The malicious pod remains in the cluster, leading to a persistent CrashLoopBackOff state that prevents any other workflows from being processed. The issue is resolved in versions 3.7.14 and 4.0.5.

## Affected products

- argoproj Argo Workflows >= 3.6.5, <= 3.6.19; >= 3.7.0, <= 3.7.13; >= 4.0.0, <= 4.0.4
- Red Hat Red Hat OpenShift AI (RHOAI)

## Identifiers

- CVE-2026-40886
- GHSA-5jv8-h7qh-rf5p
- GO-2026-5148

## Timeline

- 2026-04-23: disclosed
- 2026-04-23: advisory
- 2026-04-23: patched

## References

- [https://github.com/argoproj/argo-workflows/security/advisories/GHSA-5jv8-h7qh-rf5p](https://github.com/argoproj/argo-workflows/security/advisories/GHSA-5jv8-h7qh-rf5p)
- [https://access.redhat.com/security/cve/CVE-2026-40886](https://access.redhat.com/security/cve/CVE-2026-40886)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2461236](https://bugzilla.redhat.com/show_bug.cgi?id=2461236)
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40886.json](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40886.json)

## Related threats

- [Argo Workflows privilege escalation via ArtifactGC PodSpecPatch](https://junglewise.ai/threats/cve-2026-54526-argo-workflows-privilege-escalation-via-artifactgc-podspecpatch)
- [Argo Workflows missing authorization in Sync ConfigMap Provider](https://junglewise.ai/threats/cve-2026-42297-argo-workflows-missing-authorization-in-sync-configmap-provider)
- [Argo Workflows authorization bypass in templateReferencing Strict mode](https://junglewise.ai/threats/cve-2026-42296-argo-workflows-authorization-bypass-in-templatereferencing-strict)
- [Argo Workflows plaintext credential leak in workflow logs](https://junglewise.ai/threats/cve-2026-42295-argo-workflows-plaintext-credential-leak-in-workflow-logs)
- [Argo Workflows denial of service in Webhook Interceptor](https://junglewise.ai/threats/cve-2026-42294-argo-workflows-denial-of-service-in-webhook-interceptor)