CVE-2026-42294: Argo Workflows denial of service in Webhook Interceptor

CVE-2026-42294 · Severity: high · CVSS 7.5 · Published 2026-05-09

Argo Workflows is an open-source engine for orchestrating parallel jobs on Kubernetes. A vulnerability in its webhook processing component allows an unauthenticated attacker to crash the Argo Server by sending a specially crafted, large request. This results in a denial of service, preventing users from managing workflows or accessing the API.

Technologies: Argo Project Argo Workflows, github.com/argoproj/argo-workflows (Go), github.com/argoproj/argo-workflows/v2 (Go), github.com/argoproj/argo-workflows/v3 (Go), github.com/argoproj/argo-workflows/v4 (Go). Vendors: Argo Project, Go.

Quick answers

Is CVE-2026-42294 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-42294 being exploited in the wild.
How severe is CVE-2026-42294?
High severity, with a CVSS score of 7.5, published 9 May 2026.
Which products and versions are affected?
Argo Project Argo Workflows < 3.7.14, >= 4.0.0, < 4.0.5, >= 4.0.0, < 4.0.5; 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) < 3.7.14, SEMVER:introduced=0,fixed=3.7.14; and 1 more.
Is there a fix for CVE-2026-42294?
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-2026-42294 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-42294?
Check whether you run Argo Project Argo 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
    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
    go get github.com/argoproj/argo-workflows/v4@v4.0.5

Technical details

The vulnerability is an 'Allocation of Resources Without Limits or Throttling' (CWE-770) within the Webhook Interceptor (`server/auth/webhook/interceptor.go`). The `addWebhookAuthorization` function uses `io.ReadAll` to load the entire HTTP request body into memory before performing authentication or signature verification. Because the `/api/v1/events/` endpoint is publicly accessible, a remote, unauthenticated attacker can send a multi-gigabyte payload, triggering an Out-Of-Memory (OOM) crash of the Argo Server. The issue is fixed in versions 3.7.14 and 4.0.5 by implementing request body size limits.

Affected products

  • argoproj argo-workflows/v3 < 3.7.14
  • argoproj argo-workflows/v4 >= 4.0.0, < 4.0.5

Identifiers

  • CVE-2026-42294
  • GHSA-jcc8-g2q4-9fxq
  • GO-2026-5462

Timeline

  • 2026-04-23: disclosed: Initial disclosure to maintainers
  • 2026-05-04: advisory: GitHub Advisory published
  • 2026-05-09: advisory: NVD published CVE-2026-42294
  • 2026-07-21: other: Advisory updated

References

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