diff --git a/.github/.copilot/breadcrumbs/2026-08-19-2233-upgrade-go-toolchain-1.26.6.md b/.github/.copilot/breadcrumbs/2026-08-19-2233-upgrade-go-toolchain-1.26.6.md
new file mode 100644
index 00000000..35187f40
--- /dev/null
+++ b/.github/.copilot/breadcrumbs/2026-08-19-2233-upgrade-go-toolchain-1.26.6.md
@@ -0,0 +1,38 @@
+# Go 1.26.6 Toolchain Upgrade
+
+## Requirements
+- Upgrade the same files changed by PR #403 from Go 1.25.13 to Go 1.26.6.
+
+## Additional comments from user
+- Upgrade same files from PR #403 to 1.26.6.
+
+## Plan
+1. Update the Go directive, Docker builder images, and CI Go version variables.
+2. Verify all targeted references are updated and no stale references remain.
+3. Run applicable validation, secret scanning, and CodeQL checks.
+
+## Decisions
+- Keep the scope identical to PR #403: the four Dockerfiles, six workflows, and `go.mod`.
+
+## Implementation Details
+- Updated the Go directive and Docker builder image tags to `1.26.6`.
+- Updated the six workflow `GO_VERSION` values to `1.26.6`.
+
+## Changes Made
+- `go.mod`
+- `docker/hub-net-controller-manager.Dockerfile`
+- `docker/mcs-controller-manager.Dockerfile`
+- `docker/member-net-controller-manager.Dockerfile`
+- `docker/net-crd-installer.Dockerfile`
+- `.github/workflows/go.yml`
+- `.github/workflows/build-publish-mcr.yml`
+- `.github/workflows/unit-integration-tests.yml`
+- `.github/workflows/trivy.yml`
+- `.github/workflows/e2e-tests.yml`
+- `.github/workflows/publish-image.yml`
+
+## Before/After Comparison
+- Go 1.25.13 references in the PR #403 files are now Go 1.26.6.
+
+## References
+- PR #403: Go toolchain bump from 1.25.12 to 1.25.13.
diff --git a/.github/workflows/build-publish-mcr.yml b/.github/workflows/build-publish-mcr.yml
index 87a1817d..fbcc423e 100644
--- a/.github/workflows/build-publish-mcr.yml
+++ b/.github/workflows/build-publish-mcr.yml
@@ -17,7 +17,7 @@ env:
   # `public` indicates images to MCR wil be publicly available, and will be removed in the final MCR images
   REGISTRY_REPO: public/aks/fleet
 
-  GO_VERSION: '1.25.13'
+  GO_VERSION: '1.26.6'
 
 jobs:
   prepare-variables:
diff --git a/.github/workflows/e2e-tests.yml b/.github/workflows/e2e-tests.yml
index 08d5eff5..95c30a24 100644
--- a/.github/workflows/e2e-tests.yml
+++ b/.github/workflows/e2e-tests.yml
@@ -13,7 +13,7 @@ permissions:
   contents: read
 
 env:
-  GO_VERSION: '1.25.13'
+  GO_VERSION: '1.26.6'
 
 jobs:
   detect-noop:
diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index 1fdf629c..c47ce411 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -14,7 +14,7 @@ on:
 
 env:
   # Common versions
-  GO_VERSION: '1.25.13'
+  GO_VERSION: '1.26.6'
 
 jobs:
 
diff --git a/.github/workflows/publish-image.yml b/.github/workflows/publish-image.yml
index bebfa517..e2d94f04 100644
--- a/.github/workflows/publish-image.yml
+++ b/.github/workflows/publish-image.yml
@@ -19,7 +19,7 @@ env:
   REGISTRY: ghcr.io
   IMAGE_VERSION: latest
 
-  GO_VERSION: '1.25.13'
+  GO_VERSION: '1.26.6'
 
 jobs:
   export-registry:
diff --git a/.github/workflows/trivy.yml b/.github/workflows/trivy.yml
index 8ddcd6a4..bccd26d0 100644
--- a/.github/workflows/trivy.yml
+++ b/.github/workflows/trivy.yml
@@ -21,7 +21,7 @@ env:
   MEMBER_NET_CONTROLLER_MANAGER_IMAGE_NAME: member-net-controller-manager
   MCS_CONTROLLER_MANAGER_IMAGE_NAME: mcs-controller-manager
 
-  GO_VERSION: '1.25.13'
+  GO_VERSION: '1.26.6'
 
 jobs:
   export-registry:
diff --git a/.github/workflows/unit-integration-tests.yml b/.github/workflows/unit-integration-tests.yml
index d40574ed..55d7cd09 100644
--- a/.github/workflows/unit-integration-tests.yml
+++ b/.github/workflows/unit-integration-tests.yml
@@ -16,7 +16,7 @@ permissions:
   contents: read
 
 env:
-  GO_VERSION: '1.25.13'
+  GO_VERSION: '1.26.6'
 
 jobs:
   detect-noop:
diff --git a/docker/hub-net-controller-manager.Dockerfile b/docker/hub-net-controller-manager.Dockerfile
index 3486788e..87d2e4c4 100644
--- a/docker/hub-net-controller-manager.Dockerfile
+++ b/docker/hub-net-controller-manager.Dockerfile
@@ -1,5 +1,5 @@
 # Build the hub-net-controller-manager binary
-FROM mcr.microsoft.com/oss/go/microsoft/golang:1.25.13 AS builder
+FROM mcr.microsoft.com/oss/go/microsoft/golang:1.26.6 AS builder
 
 ARG GOOS=linux
 ARG GOARCH=amd64
diff --git a/docker/mcs-controller-manager.Dockerfile b/docker/mcs-controller-manager.Dockerfile
index 5f7daf9e..e6fe3123 100644
--- a/docker/mcs-controller-manager.Dockerfile
+++ b/docker/mcs-controller-manager.Dockerfile
@@ -1,5 +1,5 @@
 # Build the mcs-controller-manager binary
-FROM mcr.microsoft.com/oss/go/microsoft/golang:1.25.13 AS builder
+FROM mcr.microsoft.com/oss/go/microsoft/golang:1.26.6 AS builder
 
 ARG GOOS=linux
 ARG GOARCH=amd64
diff --git a/docker/member-net-controller-manager.Dockerfile b/docker/member-net-controller-manager.Dockerfile
index 488ecca5..c860af3a 100644
--- a/docker/member-net-controller-manager.Dockerfile
+++ b/docker/member-net-controller-manager.Dockerfile
@@ -1,5 +1,5 @@
 # Build the member-net-controller-manager binary
-FROM mcr.microsoft.com/oss/go/microsoft/golang:1.25.13 AS builder
+FROM mcr.microsoft.com/oss/go/microsoft/golang:1.26.6 AS builder
 
 ARG GOOS=linux
 ARG GOARCH=amd64
diff --git a/docker/net-crd-installer.Dockerfile b/docker/net-crd-installer.Dockerfile
index a2384176..521d4d32 100644
--- a/docker/net-crd-installer.Dockerfile
+++ b/docker/net-crd-installer.Dockerfile
@@ -1,5 +1,5 @@
 # Build the net-crd-installer binary
-FROM mcr.microsoft.com/oss/go/microsoft/golang:1.25.13 AS builder
+FROM mcr.microsoft.com/oss/go/microsoft/golang:1.26.6 AS builder
 
 ARG GOOS=linux
 ARG GOARCH=amd64
diff --git a/go.mod b/go.mod
index 3c2e7dbc..6b64400e 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module go.goms.io/fleet-networking
 
-go 1.25.13
+go 1.26.6
 
 require go.goms.io/fleet v0.14.0