Kyverno: ServiceAccount token leaked to external servers via apiCall service URL

Exploitation

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

CVSS

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

EPSS

• CVE-2026-41323: 0.56% estimated exploitation activity in the next 30 days; percentile 46.65 (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 Kyverno's apiCall feature in ClusterPolicy automatically attaches the admission controller's ServiceAccount token to outgoing HTTP requests. The service URL has no validation — it can point anywhere, including attacker-controlled servers. Since the admission controller SA has permissions to patch webhook configurations, a stolen token leads to full cluster compromise. Affected version Tested on Kyverno v1.17.1 (Helm chart default installation). Likely affects all versions with apiCall service support. Details There are two issues that combine into one attack chain. The first is in pkg/engine/apicall/executor.go around line 138. The service URL from the policy spec goes straight into http.NewRequestWithContext(): No scheme check, no IP restriction, no allowlist. The policy validation webhook (pkg/validation/policy/validate.go) only looks at JMESPath syntax. The second is at lines 155-159 of the same file. If the request doesn't already have an Authorization header, Kyverno…

Published by the source

16 Apr 2026, 21:36 UTC

Last modified by the source

24 Apr 2026, 21:02 UTC

Source last checked

26 Oct 2026, 15:19 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-f9g8-6ppc-pqq4

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# Patch Next advisory brief: CVE-2026-41323

Advisory: Kyverno: ServiceAccount token leaked to external servers via apiCall service URL
IDs: CVE-2026-41323, GHSA-f9g8-6ppc-pqq4
Record: https://patchnext.com/advisories/cve-2026-41323 (revision 1, source checked 26 Oct 2026, 15:19 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/kyverno/kyverno 1.17.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/kyverno/kyverno: affected < 1.17.0; fixed in 1.17.0

## Suggested inspection (read-only)
- Go github.com/kyverno/kyverno: 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/kyverno/kyverno.
- 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-f9g8-6ppc-pqq4 (GitHub-reviewed advisory GHSA-f9g8-6ppc-pqq4 lists affected ranges: Go github.com/kyverno/kyverno >=0 <1.17.0)

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