diff --git a/src/application/AppBundleExecutable.ts b/src/application/AppBundleExecutable.ts
index 955ed7a239..42a18c594f 100644
--- a/src/application/AppBundleExecutable.ts
+++ b/src/application/AppBundleExecutable.ts
@@ -1,5 +1,5 @@
 import { lstat, opendir, readFile, realpath, stat } from "node:fs/promises";
-import { join } from "node:path";
+import { join, sep } from "node:path";
 
 import { z } from "zod";
 
@@ -357,9 +357,11 @@ const parseBinaryPlistExecutable = (plist: Buffer): string => {
   return executableName(decodeBinaryPlistValue(plist, plan));
 };
 
+/** Names are one local path component; backslash is literal on POSIX hosts. */
 const isSafeExecutableName = (name: string): boolean =>
   name.length > 0 &&
   name !== "." &&
   name !== ".." &&
   !name.includes("\0") &&
-  !/[/\\]/u.test(name);
+  !name.includes("/") &&
+  (sep !== "\\" || !name.includes("\\"));
diff --git a/tests/acceptance/appBundleBackslashCli.test.ts b/tests/acceptance/appBundleBackslashCli.test.ts
new file mode 100644
index 0000000000..49fb580caf
--- /dev/null
+++ b/tests/acceptance/appBundleBackslashCli.test.ts
@@ -0,0 +1,48 @@
+import {
+  copyFile,
+  mkdir,
+  readFile,
+  realpath,
+  writeFile,
+} from "node:fs/promises";
+import { join } from "node:path";
+import { expect } from "vitest";
+import { parseEvidence } from "../../src/domain/evidence.js";
+import { createTestTempDirectory } from "../fixtures/temporaryDirectory.js";
+import { cliTest } from "../support/cli/cliFixture.js";
+
+cliTest.skipIf(process.platform !== "darwin")(
+  "inspects a bundle with a literal backslash in its executable name",
+  async ({ cli }) => {
+    const root = await createTestTempDirectory("rea-app-backslash-");
+    const app = join(root, "Back.app");
+    const programs = join(app, "Contents", "MacOS");
+    const executable = join(programs, "App\\Name");
+    await mkdir(programs, { recursive: true });
+    await writeFile(
+      join(app, "Contents", "Info.plist"),
+      "<plist><dict><key>CFBundleExecutable</key><string>App\\Name</string></dict></plist>",
+    );
+    await copyFile("/usr/bin/true", executable);
+    const original = await readFile(executable);
+    const canonical = await realpath(executable);
+    for (const command of [
+      "inspect-macho",
+      "list-architectures",
+      "inspect-signature",
+    ]) {
+      const result = await cli.run({
+        arguments: [command, app, "--json"],
+        environment:
+          process.env.DEVELOPER_DIR === undefined
+            ? {}
+            : { DEVELOPER_DIR: process.env.DEVELOPER_DIR },
+      });
+      expect(result.exitCode, result.stderr).toBe(0);
+      const evidence = parseEvidence(result.json);
+      expect(evidence.caller_input_path).toBe(app);
+      expect(evidence.subject?.local_path).toBe(canonical);
+    }
+    expect((await readFile(executable)).equals(original)).toBe(true);
+  },
+);
diff --git a/tests/boundary/filesystem/binaryTarget.test.ts b/tests/boundary/filesystem/binaryTarget.test.ts
index f4ef009fd0..3bfab1c2e7 100644
--- a/tests/boundary/filesystem/binaryTarget.test.ts
+++ b/tests/boundary/filesystem/binaryTarget.test.ts
@@ -662,6 +662,48 @@ describe("binary target I/O: filesystem and app bundle target resolution", () =>
     });
   });
 
+  it.skipIf(process.platform === "win32")(
+    "preserves a literal backslash in a POSIX app executable name",
+    async () => {
+      const directory = await createTestTempDirectory("rea-target-");
+      const app = join(directory, "Back.app");
+      const programs = join(app, "Contents", "MacOS");
+      const executable = join(programs, "App\\Name");
+      await mkdir(programs, { recursive: true });
+      await writeFile(
+        join(app, "Contents", "Info.plist"),
+        "<plist><dict><key>CFBundleExecutable</key><string>App\\Name</string></dict></plist>",
+      );
+      await writeFile(executable, thinMach(0xfeedfacf, 0x0100000c));
+      const result = await parseBinaryTarget(app, {
+        cwd: directory,
+        hostArchitecture: "arm64",
+      });
+      expect(result.ok && result.value).toMatchObject({
+        path: await realpath(executable),
+        format: "mach-o",
+      });
+    },
+  );
+
+  it.skipIf(process.platform !== "win32")(
+    "rejects a Windows separator in an app executable declaration",
+    async () => {
+      const directory = await createTestTempDirectory("rea-target-");
+      const app = join(directory, "Broken.app");
+      await mkdir(join(app, "Contents", "MacOS"), { recursive: true });
+      await writeFile(
+        join(app, "Contents", "Info.plist"),
+        "<plist><dict><key>CFBundleExecutable</key><string>..\\escape</string></dict></plist>",
+      );
+      const result = await parseBinaryTarget(app, { cwd: directory });
+      expect(result).toMatchObject({
+        ok: false,
+        error: { reason: "app has an unsafe CFBundleExecutable" },
+      });
+    },
+  );
+
   it.each([
     ["missing plist", undefined],
     ["missing executable name", "<plist><dict></dict></plist>"],