ArgoCD ServerSideDiff is vulnerable to Kubernetes Secret Extraction

Exploitation

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

CVSS

9.6 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

EPSS

• CVE-2026-42880: 0.65% estimated exploitation activity in the next 30 days; percentile 50.98 (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.

Summary There is a missing authorization and data-masking gap in Argo CD's ServerSideDiff endpoint that allows an attacker with read-only access to extract plaintext Kubernetes Secret data from etcd via the Kubernetes API server's Server-Side Apply dry-run mechanism. Details Argo CD masks Secret data in every endpoint that returns Kubernetes resource state except one. All the other endpoints such as GetManifests, GetManifestsWithFiles, GetResource and PatchResource utilize hideSecretData() to mask the returned secret value. The vulnerable function ServerSideDiff gRPC/REST endpoint (/application.ApplicationService/ServerSideDiff) constructs its response with raw, unmasked PredictedLive and NormalizedLive states: A user only requires RBAC to call this ServerSideDiff function. Every authenticated Argo CD user has get access via the default role:catch-all policy. However, Argo CD has a defense layer called removeWebhookMutation() that normally strips non-Argo CD-managed fields from the…

Published by the source

7 May 2026, 01:56 UTC

Last modified by the source

11 May 2026, 13:30 UTC

Source last checked

26 Oct 2026, 15:20 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3v3m-wc6v-x4x3

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# Patch Next advisory brief: CVE-2026-42880

Advisory: ArgoCD ServerSideDiff is vulnerable to Kubernetes Secret Extraction
IDs: CVE-2026-42880, GHSA-3v3m-wc6v-x4x3
Record: https://patchnext.com/advisories/cve-2026-42880 (revision 1, source checked 26 Oct 2026, 15:20 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.6)
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-cd/v3 3.3.9, 3.2.11. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/argoproj/argo-cd/v3: affected >= 3.2.0, < 3.2.11; >= 3.3.0, < 3.3.9; fixed in 3.3.9, 3.2.11

## Suggested inspection (read-only)
- Go github.com/argoproj/argo-cd/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-cd/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-3v3m-wc6v-x4x3 (GitHub-reviewed advisory GHSA-3v3m-wc6v-x4x3 lists affected ranges: Go github.com/argoproj/argo-cd/v3 >=3.2.0 =3.3.0 <3.3.9)

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