---
id: "CVE-2026-115539"
page: "https://infrastack.ai/live/CVE-2026-115539"
kind: "vulnerability"
aliases: ["CVE-2026-115539"]
title: "SwarmKit: proxy lets a worker node obtain a manager certificate"
severity: "high"
cvss: 7.7
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "github.com/moby/swarmkit/v2", "fixed": [], "affected": "< 2.1.3 (with grpc-go >= 1.39)", "ecosystem": "go"}, {"name": "github.com/moby/moby/v2", "fixed": [], "affected": "<= v2.0.0-beta.28", "ecosystem": "go"}]
ecosystems: []
tags: ["docker-swarm", "grpc-go", "infrastructure", "swarmkit"]
not_affected_if: ["grpc-go-below-1.39", "no-swarm-cluster"]
published_at: "2026-11-10T20:18:03+00:00"
first_seen_at: "2026-11-10T20:46:01+00:00"
updated_at: "2026-11-10T21:03:41+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-115539", "first_seen_at": "2026-11-10T20:46:01+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-11-10T21:03:41+00:00"}]
exploit_sources: []
---

# SwarmKit: proxy lets a worker node obtain a manager certificate

Link for people: https://infrastack.ai/live/CVE-2026-115539 (this .md is for agents)

SwarmKit's Cluster-API proxy can overwrite a forwarded client's TLS identity with an intermediary manager's identity, during a short window after a leader change. An attacker holding a valid worker node certificate and key can obtain a manager node certificate for their own key, escalating from worker to manager.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- go:github.com/moby/swarmkit/v2 affected < 2.1.3 (with grpc-go >= 1.39) fixed no fixed version listed
- go:github.com/moby/moby/v2 affected <= v2.0.0-beta.28 fixed no fixed version listed

## How to check

Check whether you run Docker Swarm / SwarmKit managers: 'docker info' (Swarm: active) and 'docker version'. For Go builds, run 'go list -m all' and look for github.com/moby/swarmkit/v2 < 2.1.3 together with google.golang.org/grpc >= 1.39. Exposure also needs an attacker holding a valid worker node certificate and key, during a short window after a leader change.

## Fix

No patched release is listed in the advisory (Patched versions: None). The advisory marks swarmkit/v2 < 2.1.3 as affected, but the releases page showed only v2.1.2 when checked. Watch moby/swarmkit for v2.1.3 and rebuild Docker/Moby against it.

## Timeline

- 2026-11-10T20:46:01+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-115539
- 2026-11-10T21:03:41+00:00 analyst — Read GHSA-628g-hv7f-pgjc. Affected: swarmkit/v2 <2.1.3, swarmkit >= v1.12.1-0.20220307221335-616e8db4c3b0, moby/moby/v2 <= v2.0.0-beta.28, with grpc-go >= 1.39. Advisory lists Patched: None; releases page shows only v2.1.2, so no fixed release confirmed. No PoC, no exploitation seen.

## Documents

- [advisory] Vendor advisory: github.com https://github.com/moby/swarmkit/security/advisories/GHSA-628g-hv7f-pgjc

## From the sources

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.

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