Description
SwarmKit's Cluster-API proxy can overwrite a forwarded client's TLS identity with an intermediary manager's identity. WithMetadataForwardTLSInfo replaces outgoing metadata with a copy of the incoming metadata, discarding the redirect guard's changes when built with grpc-go 1.39 or later. During a short window after a leader change, two proxy hops through managers with inconsistent views of the leader can allow an attacker possessing a valid worker node TLS certificate and private key to obtain a manager node certificate for the attacker's own key, escalating privileges from worker to manager. Applications built with an affected SwarmKit version and grpc-go 1.39 or later are impacted.
Published: 2026-11-10
Score: 7.7 High
EPSS: n/a
KEV: No
AI Analysis

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Remediation

Vendor Solution

Upgrade applications using github.com/moby/swarmkit/v2 to version 2.1.3 or later.

Tracking

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Advisories

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History

Tue, 10 Nov 2026 20:15:00 +0000

Type Values Removed Values Added
Description SwarmKit's Cluster-API proxy can overwrite a forwarded client's TLS identity with an intermediary manager's identity. WithMetadataForwardTLSInfo replaces outgoing metadata with a copy of the incoming metadata, discarding the redirect guard's changes when built with grpc-go 1.39 or later. During a short window after a leader change, two proxy hops through managers with inconsistent views of the leader can allow an attacker possessing a valid worker node TLS certificate and private key to obtain a manager node certificate for the attacker's own key, escalating privileges from worker to manager. Applications built with an affected SwarmKit version and grpc-go 1.39 or later are impacted.
Title Cluster-API proxy overwrites forwarded client identity with its own
Weaknesses CWE-441
References
Metrics cvssV4_0

{'score': 7.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}


Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: Docker

Published:

Updated: 2026-11-10T19:57:40.523Z

Reserved: 2026-10-22T19:45:05.740Z

Link: CVE-2026-115539

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-10T20:18:03.897

Modified: 2026-11-10T20:18:03.897

Link: CVE-2026-115539

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses
  • CWE-441

    Unintended Proxy or Intermediary ('Confused Deputy')