Add support for linux/arm64

Recognize the linux/arm64 platform so the CodeQL CLI is accepted on
Arm64 Linux runners and the native per-platform bundle
codeql-bundle-linux-arm64.tar.zst is resolved, rather than falling
through to the combined all-platforms gzip fallback (which deliberately
omits arm64).

Add ["linux", "arm64"] to the supported platforms and make the linux
bundle name arch-aware. Keep the download mock faithful and cover the
new arch branch with tests.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

CHANGELOG.md

@@ -4,7 +4,7 @@ See the [releases page](https://github.com/github/codeql-action/releases) for th
 
 ## [UNRELEASED]
 
-No user facing changes.
+- The CodeQL Action now supports running on Linux Arm64 runners, downloading the native `linux-arm64` CodeQL bundle. [#4072](https://github.com/github/codeql-action/pull/4072)
 
 ## 4.37.5 - 03 Aug 2026
 

lib/entry-points.js

@@ -147777,6 +147777,7 @@ var toolrunner3 = __toESM(require_toolrunner());
 // src/cli-errors.ts
 var SUPPORTED_PLATFORMS = [
   ["linux", "x64"],
+  ["linux", "arm64"],
   ["win32", "x64"],
   ["darwin", "x64"],
   ["darwin", "arm64"]
@@ -150946,7 +150947,7 @@ function getCodeQLBundleName(compressionMethod) {
   if (process.platform === "win32") {
     platform2 = "win64";
   } else if (process.platform === "linux") {
-    platform2 = "linux64";
+    platform2 = process.arch === "arm64" ? "linux-arm64" : "linux64";
   } else if (process.platform === "darwin") {
     platform2 = "osx64";
   } else {

src/cli-errors.test.ts

@@ -128,7 +128,6 @@ test("CliError constructor with empty stderr", (t) => {
 
 for (const [platform, arch] of [
   ["weird_plat", "x64"],
-  ["linux", "arm64"],
   ["win32", "arm64"],
 ]) {
   test.serial(

src/cli-errors.ts

@@ -8,6 +8,7 @@ import { ConfigurationError } from "./util";
 
 const SUPPORTED_PLATFORMS = [
   ["linux", "x64"],
+  ["linux", "arm64"],
   ["win32", "x64"],
   ["darwin", "x64"],
   ["darwin", "arm64"],

src/setup-codeql.test.ts

@@ -120,24 +120,35 @@ test.serial(
 const LINKED_BUNDLE_TEST_CASES = [
   {
     platform: "linux",
+    arch: "x64",
     tarSupportsZstd: true,
     expectedBundleName: "codeql-bundle-linux64.tar.zst",
     expectedCompressionMethod: "zstd",
   },
+  {
+    platform: "linux",
+    arch: "arm64",
+    tarSupportsZstd: true,
+    expectedBundleName: "codeql-bundle-linux-arm64.tar.zst",
+    expectedCompressionMethod: "zstd",
+  },
   {
     platform: "darwin",
+    arch: "arm64",
     tarSupportsZstd: true,
     expectedBundleName: "codeql-bundle-osx64.tar.zst",
     expectedCompressionMethod: "zstd",
   },
   {
     platform: "win32",
+    arch: "x64",
     tarSupportsZstd: true,
     expectedBundleName: "codeql-bundle-win64.tar.gz",
     expectedCompressionMethod: "gzip",
   },
   {
     platform: "linux",
+    arch: "x64",
     tarSupportsZstd: false,
     expectedBundleName: "codeql-bundle-linux64.tar.gz",
     expectedCompressionMethod: "gzip",
@@ -146,6 +157,7 @@ const LINKED_BUNDLE_TEST_CASES = [
 
 for (const {
   platform,
+  arch,
   tarSupportsZstd,
   expectedBundleName,
   expectedCompressionMethod,
@@ -155,6 +167,7 @@ for (const {
     async (t) => {
       const features = createFeatures([]);
       sinon.stub(process, "platform").value(platform);
+      sinon.stub(process, "arch").value(arch);
 
       await withTmpDir(async (tmpDir) => {
         setupActionsVars(tmpDir, tmpDir);

src/setup-codeql.ts

@@ -75,7 +75,7 @@ export function getCodeQLBundleName(
   if (process.platform === "win32") {
     platform = "win64";
   } else if (process.platform === "linux") {
-    platform = "linux64";
+    platform = process.arch === "arm64" ? "linux-arm64" : "linux64";
   } else if (process.platform === "darwin") {
     platform = "osx64";
   } else {

src/testing-utils.ts

@@ -936,7 +936,9 @@ export function mockBundleDownloadApi({
     process.platform === "win32"
       ? "win64"
       : process.platform === "linux"
-        ? "linux64"
+        ? process.arch === "arm64"
+          ? "linux-arm64"
+          : "linux64"
         : "osx64";
 
   const baseUrl = apiDetails?.url ?? "https://example.com";