Argo Vulnerable to Unauthenticated Memory Exhaustion (DoS) in Webhook Interceptor

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.2 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-42294: 0.60% estimated exploitation activity in the next 30 days; percentile 48.73 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Severity: Medium Component: Webhook Interceptor (server/auth/webhook) Vulnerability Type: Denial of Service (DoS) Description The Webhook Interceptor loads the entire request body into memory before authenticating the request or verifying its signature. This occurs on the /api/v1/events/ endpoint, which is publicly accessible (albeit intended for webhooks). An attacker can send a request with an extremely large body (e.g., multiple gigabytes), causing the Argo Server to allocate excessive memory, potentially leading to an Out-Of-Memory (OOM) crash and denial of service. Vulnerable Code In server/auth/webhook/interceptor.go: The io.ReadAll call happens before the signature verification loop. Impact - Service Availability: An attacker can crash the Argo Server, disrupting workflow execution and API access for all users. PoC (Conceptual) 1. Target the webhook endpoint: POST /api/v1/events/some-namespace 2. Send a Content-Length: 1000000000 (1GB) header. 3. Stream 1GB of random data. 4.…

Published by the source

4 May 2026, 20:11 UTC

Last modified by the source

21 Jul 2026, 14:54 UTC

Source last checked

26 Oct 2026, 15:27 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-jcc8-g2q4-9fxq

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# Patch Next advisory brief: CVE-2026-42294

Advisory: Argo Vulnerable to Unauthenticated Memory Exhaustion (DoS) in Webhook Interceptor
IDs: CVE-2026-42294, GHSA-jcc8-g2q4-9fxq
Record: https://patchnext.com/advisories/cve-2026-42294 (revision 1, source checked 26 Oct 2026, 15:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/argoproj/argo-workflows/v4 4.0.5; github.com/argoproj/argo-workflows/v3 3.7.14. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/argoproj/argo-workflows/v4: affected >= 4.0.0, < 4.0.5; fixed in 4.0.5
- Go github.com/argoproj/argo-workflows/v3: affected < 3.7.14; fixed in 3.7.14

## Suggested inspection (read-only)
- Go github.com/argoproj/argo-workflows/v4: check the installed version with your package manager.
- Go github.com/argoproj/argo-workflows/v3: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/argoproj/argo-workflows/v4, github.com/argoproj/argo-workflows/v3.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-jcc8-g2q4-9fxq (GitHub-reviewed advisory GHSA-jcc8-g2q4-9fxq lists affected ranges: Go github.com/argoproj/argo-workflows/v3 >=0 =4.0.0 <4.0.5)

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