[client, relay, management] Bump go version to 1.26 and go-quic to v0.62.0 (#7359)

* Bump go version to 1.26 and go-quic to v0.62.0
* Replace deprecated ecdsa public key assembly and add tests for jwt
* Update goversioninfo
* Pin go toolchain to 1.26.7

.devcontainer/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.25-bookworm
+FROM golang:1.26.7-bookworm
 
 RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
     && apt-get -y install --no-install-recommends\

.github/workflows/golang-test-linux.yml

@@ -233,7 +233,7 @@ jobs:
             -e GOCACHE=${CONTAINER_GOCACHE} \
             -e GOMODCACHE=${CONTAINER_GOMODCACHE} \
             -e CONTAINER=${CONTAINER} \
-            golang:1.25-alpine \
+            golang:1.26.7-alpine \
             sh -c ' \
               apk update; apk add --no-cache \
                 ca-certificates iptables ip6tables dbus dbus-dev libpcap-dev build-base; \

.github/workflows/release.yml

@@ -215,7 +215,7 @@ jobs:
           echo "GPG_RPM_KEY_FILE=/tmp/gpg-rpm-signing-key.asc" >> $GITHUB_ENV
 
       - name: Install goversioninfo
-        run: go install github.com/josephspurrier/goversioninfo/cmd/goversioninfo@233067e
+        run: go install github.com/josephspurrier/goversioninfo/cmd/goversioninfo@b66839b # v1.7.0
       - name: Generate windows syso amd64
         run: goversioninfo  -icon client/ui/build/windows/icon.ico -manifest client/manifest.xml -product-name ${{ env.PRODUCT_NAME }} -copyright "${{ env.COPYRIGHT }}" -ver-major ${{ steps.semver_parser.outputs.major }} -ver-minor ${{ steps.semver_parser.outputs.minor }} -ver-patch ${{ steps.semver_parser.outputs.patch }} -ver-build 0 -file-version ${{ steps.semver_parser.outputs.fullversion }}.0 -product-version ${{ steps.semver_parser.outputs.fullversion }}.0 -o client/resources_windows_amd64.syso
       - name: Generate windows syso arm64
@@ -435,7 +435,7 @@ jobs:
           tar -xf llvm-mingw-20250709-ucrt-ubuntu-22.04-x86_64.tar.xz
           echo "/tmp/llvm-mingw-20250709-ucrt-ubuntu-22.04-x86_64/bin" >> $GITHUB_PATH
       - name: Install goversioninfo
-        run: go install github.com/josephspurrier/goversioninfo/cmd/goversioninfo@233067e
+        run: go install github.com/josephspurrier/goversioninfo/cmd/goversioninfo@b66839b # v1.7.0
       - name: Install wails3 CLI
         # Version derived from go.mod so the binding generator always matches
         # the wails runtime the binary links against.

CONTRIBUTING.md

@@ -192,7 +192,7 @@ dependencies are installed. Here is a short guide on how that can be done.
 
 ### Requirements
 
-#### Go 1.25
+#### Go 1.26
 
 Follow the installation guide from https://go.dev/
 
@@ -200,7 +200,7 @@ Follow the installation guide from https://go.dev/
 
 The desktop UI client (`client/ui`) is built with [Wails v3](https://v3.wails.io/) and a React frontend rendered in a WebView. To build it you need:
 
-- Go ≥ 1.25
+- Go ≥ 1.26
 - Node ≥ 20 and **pnpm** (`corepack enable && corepack prepare pnpm@latest --activate`)
 - The `wails3` CLI: `go install github.com/wailsapp/wails/v3/cmd/wails3@latest`
 - The `task` runner: `go install github.com/go-task/task/v3/cmd/task@latest`

client/testutil/privileged/runner_test.go

@@ -25,7 +25,7 @@ import (
 // (.github/workflows/golang-test-linux.yml, test_client_on_docker).
 const (
 	containerImage = "golang"
-	containerTag   = "1.25-alpine"
+	containerTag   = "1.26.7-alpine"
 )
 
 const (

client/ui/build/docker/Dockerfile.cross

@@ -13,7 +13,7 @@
 #   docker run --rm -v $(pwd):/app wails-cross windows amd64
 #   docker run --rm -v $(pwd):/app wails-cross windows arm64
 
-FROM golang:1.25-bookworm
+FROM golang:1.26.7-bookworm
 
 ARG TARGETARCH
 

client/ui/build/docker/Dockerfile.server

@@ -2,7 +2,7 @@
 # Multi-stage build for minimal image size
 
 # Build stage
-FROM golang:alpine AS builder
+FROM golang:1.26.7-alpine AS builder
 
 WORKDIR /app
 

combined/Dockerfile.multistage

@@ -1,4 +1,4 @@
-FROM golang:1.25-bookworm AS builder
+FROM golang:1.26.7-bookworm AS builder
 WORKDIR /app
 
 # Install build dependencies

docs/testing-privileged.md

@@ -32,7 +32,7 @@ list; both are optional and default to the full privileged suite.
 
 1. Skips immediately when it detects it is already inside the container
    (`DOCKER_CI=true`), so the privileged tests run in place instead of recursing.
-2. Otherwise spins up a `golang:1.25-alpine` container (matching CI),
+2. Otherwise spins up a `golang:1.26.7-alpine` container (matching CI),
    bind-mounts the repo and the host Go build/module caches, installs the
    required packages, and runs `go test -tags 'devcert privileged'` over the
    client packages.

e2e/harness/Dockerfile.client

@@ -3,7 +3,7 @@
 # artifact), so this mirrors its alpine runtime + entrypoint while compiling the
 # CGO-free client inline. BuildKit cache mounts keep rebuilds incremental.
 
-FROM golang:1.25-bookworm AS builder
+FROM golang:1.26.7-bookworm AS builder
 WORKDIR /src
 COPY go.mod go.sum ./
 RUN --mount=type=cache,target=/go/pkg/mod go mod download

go.mod

@@ -1,8 +1,10 @@
 module github.com/netbirdio/netbird
 
-go 1.25.5
+go 1.26.0
 
-toolchain go1.25.12
+// Pin the toolchain to a patch release >= go1.26.2
+// See https://go.dev/issue/77875.
+toolchain go1.26.7
 
 require (
 	cunicu.li/go-rosenpass v0.5.42
@@ -101,13 +103,13 @@ require (
 	github.com/pkg/sftp v1.13.9
 	github.com/prometheus/client_golang v1.23.2
 	github.com/prometheus/client_model v0.6.2
-	github.com/quic-go/quic-go v0.59.1
+	github.com/quic-go/quic-go v0.62.0
 	github.com/redis/go-redis/v9 v9.7.3
 	github.com/rs/xid v1.3.0
 	github.com/shirou/gopsutil/v4 v4.25.8
 	github.com/skratchdot/open-golang v0.0.0-20200116055534-eef842397966
 	github.com/songgao/water v0.0.0-20200317203138-2b4b6d7c09d8
-	github.com/stretchr/testify v1.11.1
+	github.com/stretchr/testify v1.12.1
 	github.com/testcontainers/testcontainers-go v0.37.0
 	github.com/testcontainers/testcontainers-go/modules/mysql v0.37.0
 	github.com/testcontainers/testcontainers-go/modules/postgres v0.37.0
@@ -289,7 +291,6 @@ require (
 	github.com/pion/transport/v2 v2.2.4 // indirect
 	github.com/pion/turn/v4 v4.1.1 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
-	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/power-devops/perfstat v0.0.0-20240221224432-82ca36839d55 // indirect
 	github.com/pquerna/otp v1.5.0 // indirect
 	github.com/prometheus/common v0.67.5 // indirect
@@ -299,7 +300,7 @@ require (
 	github.com/ryanuber/go-glob v1.0.0 // indirect
 	github.com/shopspring/decimal v1.4.0 // indirect
 	github.com/spf13/cast v1.10.0 // indirect
-	github.com/stretchr/objx v0.5.2 // indirect
+	github.com/stretchr/objx v0.5.3 // indirect
 	github.com/tinylib/msgp v1.6.3 // indirect
 	github.com/tklauser/go-sysconf v0.3.15 // indirect
 	github.com/tklauser/numcpus v0.10.0 // indirect
@@ -315,6 +316,7 @@ require (
 	go.opentelemetry.io/otel/trace v1.43.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
 	go.yaml.in/yaml/v2 v2.4.3 // indirect
+	go.yaml.in/yaml/v3 v3.0.5 // indirect
 	golang.org/x/text v0.41.0 // indirect
 	golang.org/x/tools v0.49.0 // indirect
 	golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2 // indirect

go.sum

@@ -582,8 +582,10 @@ github.com/prometheus/otlptranslator v1.0.0 h1:s0LJW/iN9dkIH+EnhiD3BlkkP5QVIUVEo
 github.com/prometheus/otlptranslator v1.0.0/go.mod h1:vRYWnXvI6aWGpsdY/mOT/cbeVRBlPWtBNDb7kGR3uKM=
 github.com/prometheus/procfs v0.19.2 h1:zUMhqEW66Ex7OXIiDkll3tl9a1ZdilUOd/F6ZXw4Vws=
 github.com/prometheus/procfs v0.19.2/go.mod h1:M0aotyiemPhBCM0z5w87kL22CxfcH05ZpYlu+b4J7mw=
-github.com/quic-go/quic-go v0.59.1 h1:0Gmua0HW1Tv7ANR7hUYwRyD0MG5OJfgvYSZasGZzBic=
+github.com/quic-go/go-ossfuzz-seeds v0.1.0 h1:APacT+iIaNF6fd8AGEiN3bT/Jtkd2jz4v4TzM7MFjy0=
-github.com/quic-go/quic-go v0.59.1/go.mod h1:upnsH4Ju1YkqpLXC305eW3yDZ4NfnNbmQRCMWS58IKU=
+github.com/quic-go/go-ossfuzz-seeds v0.1.0/go.mod h1:3IOHRbJIc+L6YKMwfDtJAM9Vj9k0YY4muhuyUYk5tbk=
+github.com/quic-go/quic-go v0.62.0 h1:ZHDjCk5OacATwGvs8PWE97CTvX7AqZiVoW7++ZOXTf8=
+github.com/quic-go/quic-go v0.62.0/go.mod h1:RAro2j2yN9a9EiPACLHT9IB2NXCvGQmmo/alT0yYI0w=
 github.com/redis/go-redis/v9 v9.7.3 h1:YpPyAayJV+XErNsatSElgRZZVCwXX9QzkKYNvO7x0wM=
 github.com/redis/go-redis/v9 v9.7.3/go.mod h1:bGUrSggJ9X9GUmZpZNEOQKaANxSGgOEBRltRTZHSvrA=
 github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
@@ -619,8 +621,8 @@ github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+
 github.com/stretchr/objx v0.2.0/go.mod h1:qt09Ya8vawLte6SNmTgCsAVtYtaKzEcn8ATUoHMkEqE=
 github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
-github.com/stretchr/objx v0.5.2 h1:xuMeJ0Sdp5ZMRXx/aWO6RZxdr3beISkG5/G/aIRr3pY=
+github.com/stretchr/objx v0.5.3 h1:jmXUvGomnU1o3W/V5h2VEradbpJDwGrzugQQvL0POH4=
-github.com/stretchr/objx v0.5.2/go.mod h1:FRsXN1f5AsAjCGJKqEizvkpNtU+EGNCLh3NxZ/8L+MA=
+github.com/stretchr/objx v0.5.3/go.mod h1:rDQraq+vQZU7Fde9LOZLr8Tax6zZvy4kuNKF+QYS+U0=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
@@ -630,8 +632,8 @@ github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.8.3/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
-github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
+github.com/stretchr/testify v1.12.1 h1:EuwCh5fleGS7H32xRwO3wRGT7DxrDhLAT6FF8MpWDWE=
-github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
+github.com/stretchr/testify v1.12.1/go.mod h1:MDEgiDPPsNp5cuIrHPPCyornHKgEVbtFUmoNlxoYthg=
 github.com/testcontainers/testcontainers-go v0.37.0 h1:L2Qc0vkTw2EHWQ08djon0D2uw7Z/PtHS/QzZZ5Ra/hg=
 github.com/testcontainers/testcontainers-go v0.37.0/go.mod h1:QPzbxZhQ6Bclip9igjLFj6z0hs01bU8lrl2dHQmgFGM=
 github.com/testcontainers/testcontainers-go/modules/mysql v0.37.0 h1:LqUos1oR5iuuzorFnSvxsHNdYdCHB/DfI82CuT58wbI=
@@ -717,6 +719,8 @@ go.uber.org/zap v1.27.0/go.mod h1:GB2qFLM7cTU87MWRP2mPIjqfIDnGu+VIO4V/SdhGo2E=
 go.yaml.in/yaml/v2 v2.4.3 h1:6gvOSjQoTB3vt1l+CU+tSyi/HOjfOjRLJ4YwYZGwRO0=
 go.yaml.in/yaml/v2 v2.4.3/go.mod h1:zSxWcmIDjOzPXpjlTTbAsKokqkDNAVtZO0WOMiT90s8=
 go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
+go.yaml.in/yaml/v3 v3.0.5 h1:N6y/pJk8buWs9NY5ERU2HSMfm+IuD/OtfdAnq6kESPw=
+go.yaml.in/yaml/v3 v3.0.5/go.mod h1:HVTZu1O7/Vkt2N+BFy8Zza+lnLsABggaTM2ZpNIGuKg=
 goauthentik.io/api/v3 v3.2023051.3 h1:NebAhD/TeTWNo/9X3/Uj+rM5fG1HaiLOlKTNLQv9Qq4=
 goauthentik.io/api/v3 v3.2023051.3/go.mod h1:nYECml4jGbp/541hj8GcylKQG1gVBsKppHy4+7G8u4U=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=

management/Dockerfile.multistage

@@ -1,4 +1,4 @@
-FROM golang:1.25-bookworm AS builder
+FROM golang:1.26.7-bookworm AS builder
 WORKDIR /app
 
 # Install build dependencies

proxy/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.25-alpine AS builder
+FROM golang:1.26.7-alpine AS builder
 WORKDIR /app
 
 RUN echo "netbird:x:1000:1000:netbird:/var/lib/netbird:/sbin/nologin" > /tmp/passwd && \

proxy/Dockerfile.multistage

@@ -1,4 +1,4 @@
-FROM golang:1.25-alpine AS builder
+FROM golang:1.26.7-alpine AS builder
 WORKDIR /app
 
 COPY go.mod go.sum ./

shared/auth/jwt/validator.go

@@ -289,36 +289,64 @@ func getPublicKey(token *jwt.Token, jwks *Jwks) (interface{}, error) {
 	return nil, errKeyNotFound
 }
 
-func getPublicKeyFromECDSA(jwk JSONWebKey) (publicKey *ecdsa.PublicKey, err error) {
+func curveFromName(crv string) (elliptic.Curve, error) {
+	switch crv {
+	case p256:
+		return elliptic.P256(), nil
+	case p384:
+		return elliptic.P384(), nil
+	case p521:
+		return elliptic.P521(), nil
+	default:
+		return nil, fmt.Errorf("unsupported elliptic curve %q", crv)
+	}
+}
+
+func getPublicKeyFromECDSA(jwk JSONWebKey) (*ecdsa.PublicKey, error) {
 	if jwk.X == "" || jwk.Y == "" || jwk.Crv == "" {
 		return nil, fmt.Errorf("ecdsa key incomplete")
 	}
 
-	var xCoordinate []byte
+	curve, err := curveFromName(jwk.Crv)
-	if xCoordinate, err = base64.RawURLEncoding.DecodeString(jwk.X); err != nil {
+	if err != nil {
 		return nil, err
 	}
 
-	var yCoordinate []byte
+	xCoordinate, err := base64.RawURLEncoding.DecodeString(jwk.X)
-	if yCoordinate, err = base64.RawURLEncoding.DecodeString(jwk.Y); err != nil {
+	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("decode ecdsa x coordinate: %w", err)
 	}
 
-	publicKey = &ecdsa.PublicKey{}
+	yCoordinate, err := base64.RawURLEncoding.DecodeString(jwk.Y)
-
+	if err != nil {
-	var curve elliptic.Curve
+		return nil, fmt.Errorf("decode ecdsa y coordinate: %w", err)
-	switch jwk.Crv {
-	case p256:
-		curve = elliptic.P256()
-	case p384:
-		curve = elliptic.P384()
-	case p521:
-		curve = elliptic.P521()
 	}
 
-	publicKey.Curve = curve
+	var x, y big.Int
-	publicKey.X = big.NewInt(0).SetBytes(xCoordinate)
+	x.SetBytes(xCoordinate)
-	publicKey.Y = big.NewInt(0).SetBytes(yCoordinate)
+	y.SetBytes(yCoordinate)
+
+	bits := curve.Params().BitSize
+	if x.BitLen() > bits {
+		return nil, fmt.Errorf("ecdsa x coordinate is %d bits, exceeds curve %s field size of %d bits", x.BitLen(), jwk.Crv, bits)
+	}
+	if y.BitLen() > bits {
+		return nil, fmt.Errorf("ecdsa y coordinate is %d bits, exceeds curve %s field size of %d bits", y.BitLen(), jwk.Crv, bits)
+	}
+
+	// Round up: P-521's field is 521 bits, so a coordinate needs 66 bytes, not 65.
+	size := (bits + 7) / 8
+
+	// Assemble the SEC 1 uncompressed point (0x04 || X || Y)
+	point := make([]byte, 1+2*size)
+	point[0] = 4
+	x.FillBytes(point[1 : 1+size])
+	y.FillBytes(point[1+size:])
+
+	publicKey, err := ecdsa.ParseUncompressedPublicKey(curve, point)
+	if err != nil {
+		return nil, fmt.Errorf("parse ecdsa public key: %w", err)
+	}
 
 	return publicKey, nil
 }

shared/auth/jwt/validator_test.go

@@ -0,0 +1,214 @@
+package jwt
+
+import (
+	"bytes"
+	"context"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"encoding/base64"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/golang-jwt/jwt/v5"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// ecdsaJWK builds a JWK for pub using uncompressed-point encoding
+func ecdsaJWK(t *testing.T, kid string, pub *ecdsa.PublicKey, crv string, size int) JSONWebKey {
+	t.Helper()
+
+	point, err := pub.Bytes()
+	require.NoError(t, err)
+	require.Len(t, point, 1+2*size)
+	require.Equal(t, byte(4), point[0], "expected uncompressed point")
+
+	return JSONWebKey{
+		Kty: "EC",
+		Kid: kid,
+		Use: "sig",
+		Crv: crv,
+		X:   base64.RawURLEncoding.EncodeToString(point[1 : 1+size]),
+		Y:   base64.RawURLEncoding.EncodeToString(point[1+size:]),
+	}
+}
+
+func TestGetPublicKeyFromECDSA_RoundTrip(t *testing.T) {
+	tests := []struct {
+		crv   string
+		curve elliptic.Curve
+		size  int
+	}{
+		{p256, elliptic.P256(), 32},
+		{p384, elliptic.P384(), 48},
+		{p521, elliptic.P521(), 66},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.crv, func(t *testing.T) {
+			priv, err := ecdsa.GenerateKey(tc.curve, rand.Reader)
+			require.NoError(t, err)
+
+			got, err := getPublicKeyFromECDSA(ecdsaJWK(t, "kid", &priv.PublicKey, tc.crv, tc.size))
+			require.NoError(t, err)
+			assert.True(t, priv.PublicKey.Equal(got), "parsed key differs from the original")
+		})
+	}
+}
+
+// TestGetPublicKeyFromECDSA_ShortCoordinate covers IdPs that strip leading zero
+// bytes from a coordinate instead of padding to the curve's field size.
+func TestGetPublicKeyFromECDSA_ShortCoordinate(t *testing.T) {
+	var (
+		priv  *ecdsa.PrivateKey
+		point []byte
+	)
+	for i := 0; i < 10000; i++ {
+		key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+		require.NoError(t, err)
+
+		p, err := key.PublicKey.Bytes()
+		require.NoError(t, err)
+
+		if p[1] == 0 || p[33] == 0 {
+			priv, point = key, p
+			break
+		}
+	}
+	require.NotNil(t, priv, "no key with a leading zero coordinate byte was generated")
+
+	jwk := JSONWebKey{
+		Kty: "EC",
+		Kid: "kid",
+		Crv: p256,
+		X:   base64.RawURLEncoding.EncodeToString(bytes.TrimLeft(point[1:33], "\x00")),
+		Y:   base64.RawURLEncoding.EncodeToString(bytes.TrimLeft(point[33:], "\x00")),
+	}
+
+	got, err := getPublicKeyFromECDSA(jwk)
+	require.NoError(t, err)
+	assert.True(t, priv.PublicKey.Equal(got))
+}
+
+func TestGetPublicKeyFromECDSA_Invalid(t *testing.T) {
+	priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	require.NoError(t, err)
+	valid := ecdsaJWK(t, "kid", &priv.PublicKey, p256, 32)
+
+	offCurve := valid
+	x, err := base64.RawURLEncoding.DecodeString(valid.X)
+	require.NoError(t, err)
+	x[31] ^= 0xff
+	offCurve.X = base64.RawURLEncoding.EncodeToString(x)
+
+	// 33 non-zero bytes is 264 bits, past P-256's 256-bit field.
+	oversized := valid
+	oversized.X = base64.RawURLEncoding.EncodeToString(bytes.Repeat([]byte{0xff}, 33))
+
+	// P-521 coordinates occupy 66 bytes but only 521 bits, so a full 66-byte
+	// 0xff value (528 bits) is over the field size without being over the byte
+	// length. Only a bit-length bound catches this.
+	overP521 := JSONWebKey{
+		Kty: "EC",
+		Crv: p521,
+		X:   base64.RawURLEncoding.EncodeToString(bytes.Repeat([]byte{0xff}, 66)),
+		Y:   base64.RawURLEncoding.EncodeToString(bytes.Repeat([]byte{0xff}, 66)),
+	}
+
+	zeroPoint := valid
+	zeroPoint.X = base64.RawURLEncoding.EncodeToString(make([]byte, 32))
+	zeroPoint.Y = base64.RawURLEncoding.EncodeToString(make([]byte, 32))
+
+	tests := []struct {
+		name        string
+		jwk         JSONWebKey
+		errContains string
+	}{
+		{name: "missing crv", jwk: JSONWebKey{Kty: "EC", X: valid.X, Y: valid.Y}},
+		{name: "missing x", jwk: JSONWebKey{Kty: "EC", Crv: p256, Y: valid.Y}},
+		{name: "unsupported curve", jwk: JSONWebKey{Kty: "EC", Crv: "P-224", X: valid.X, Y: valid.Y}, errContains: "unsupported elliptic curve"},
+		{name: "undecodable x", jwk: JSONWebKey{Kty: "EC", Crv: p256, X: "!!not base64!!!", Y: valid.Y}, errContains: "decode ecdsa x coordinate"},
+		{name: "coordinate over field size", jwk: oversized, errContains: "exceeds curve P-256 field size of 256 bits"},
+		{name: "p521 coordinate over field size", jwk: overP521, errContains: "exceeds curve P-521 field size of 521 bits"},
+		{name: "off-curve point", jwk: offCurve, errContains: "parse ecdsa public key"},
+		{name: "point at infinity", jwk: zeroPoint, errContains: "parse ecdsa public key"},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			key, err := getPublicKeyFromECDSA(tc.jwk)
+			require.Error(t, err)
+			assert.Nil(t, key)
+			if tc.errContains != "" {
+				assert.ErrorContains(t, err, tc.errContains)
+			}
+		})
+	}
+}
+
+// TestValidateAndParse_ECDSA verifies an ES256-signed token end to end, proving
+// the parsed key actually validates signatures.
+func TestValidateAndParse_ECDSA(t *testing.T) {
+	const (
+		kid      = "es256-kid"
+		issuer   = "https://issuer.example.com/"
+		audience = "netbird"
+	)
+
+	priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	require.NoError(t, err)
+
+	jwks, err := json.Marshal(Jwks{Keys: []JSONWebKey{ecdsaJWK(t, kid, &priv.PublicKey, p256, 32)}})
+	require.NoError(t, err)
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write(jwks)
+	}))
+	defer srv.Close()
+
+	token := jwt.NewWithClaims(jwt.SigningMethodES256, jwt.MapClaims{
+		"iss": issuer,
+		"aud": audience,
+		"sub": "user-1",
+		"iat": time.Now().Add(-time.Minute).Unix(),
+		"exp": time.Now().Add(time.Hour).Unix(),
+	})
+	token.Header["kid"] = kid
+
+	signed, err := token.SignedString(priv)
+	require.NoError(t, err)
+
+	v := NewValidator(issuer, []string{audience}, srv.URL, false)
+
+	parsed, err := v.ValidateAndParse(context.Background(), signed)
+	require.NoError(t, err)
+	require.True(t, parsed.Valid)
+
+	claims, ok := parsed.Claims.(jwt.MapClaims)
+	require.True(t, ok)
+	assert.Equal(t, "user-1", claims["sub"])
+
+	// A token signed by a different key of the same curve must be rejected.
+	other, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	require.NoError(t, err)
+
+	forged := jwt.NewWithClaims(jwt.SigningMethodES256, jwt.MapClaims{
+		"iss": issuer,
+		"aud": audience,
+		"sub": "user-1",
+		"iat": time.Now().Add(-time.Minute).Unix(),
+		"exp": time.Now().Add(time.Hour).Unix(),
+	})
+	forged.Header["kid"] = kid
+
+	forgedSigned, err := forged.SignedString(other)
+	require.NoError(t, err)
+
+	_, err = v.ValidateAndParse(context.Background(), forgedSigned)
+	require.Error(t, err)
+}