diff --git a/apps/desktop/src/features/score/scoreStorage.test.ts b/apps/desktop/src/features/score/scoreStorage.test.ts
index 0feec199..84ff554d 100644
--- a/apps/desktop/src/features/score/scoreStorage.test.ts
+++ b/apps/desktop/src/features/score/scoreStorage.test.ts
@@ -7,6 +7,15 @@ type TauriWindow = Window & {
 };
 
 const BRIDGE_UNAVAILABLE_MESSAGE = "Score PDFs are only available in the desktop app.";
+const INVALID_RESPONSE_MESSAGE = "Invalid score bridge response";
+
+function stubReadResponse(response: unknown): void {
+  vi.stubGlobal("window", {
+    __TAURI_INTERNALS__: {
+      invoke: async () => response
+    }
+  });
+}
 
 describe("scoreStorage bridge resolution", () => {
   afterEach(() => {
@@ -16,6 +25,45 @@ describe("scoreStorage bridge resolution", () => {
     delete tauriWindow.__TAURI_INVOKE__;
   });
 
+  it("converts a validated numeric byte array without coercing its values", async () => {
+    stubReadResponse([0, 1, 127, 254, 255]);
+
+    const result = await readScorePdf("project-1", "score-1");
+
+    expect(result).toBeInstanceOf(Uint8Array);
+    expect(Array.from(result)).toEqual([0, 1, 127, 254, 255]);
+  });
+
+  it.each([
+    ["string value", [104, "101", 108]],
+    ["negative integer", [0, -1, 255]],
+    ["integer above the byte range", [0, 256, 255]],
+    ["fractional number", [0, 1.5, 255]],
+    ["NaN", [0, Number.NaN, 255]],
+    ["infinity", [0, Number.POSITIVE_INFINITY, 255]]
+  ])("rejects a bridge array containing a %s", async (_label, response) => {
+    stubReadResponse(response);
+
+    await expect(readScorePdf("project-1", "score-1")).rejects.toThrow(
+      INVALID_RESPONSE_MESSAGE
+    );
+  });
+
+  it("stops validating after the first invalid byte", async () => {
+    const response: unknown[] = [-1, 0];
+    Object.defineProperty(response, 1, {
+      configurable: true,
+      get: () => {
+        throw new Error("validation read past the first invalid byte");
+      }
+    });
+    stubReadResponse(response);
+
+    await expect(readScorePdf("project-1", "score-1")).rejects.toThrow(
+      INVALID_RESPONSE_MESSAGE
+    );
+  });
+
   it("fails closed on every command when there is no window (non-browser runtime)", async () => {
     // Simulate a runtime without a DOM window (e.g. SSR / bundler prerender):
     // getInvoke() must take the `typeof window === "undefined"` branch and
diff --git a/apps/desktop/src/features/score/scoreStorage.ts b/apps/desktop/src/features/score/scoreStorage.ts
index 492f1259..6bf888c8 100644
--- a/apps/desktop/src/features/score/scoreStorage.ts
+++ b/apps/desktop/src/features/score/scoreStorage.ts
@@ -91,7 +91,13 @@ export async function readScorePdf(projectId: string, scoreId: string): Promise<
   if (response instanceof ArrayBuffer) {
     return new Uint8Array(response);
   }
-  if (Array.isArray(response) && response.every((byte) => typeof byte === "number")) {
+  if (Array.isArray(response)) {
+    for (let index = 0; index < response.length; index += 1) {
+      const byte = response[index];
+      if (!Number.isInteger(byte) || byte < 0 || byte > 255) {
+        throw new Error(INVALID_RESPONSE_MESSAGE);
+      }
+    }
     return Uint8Array.from(response as number[]);
   }
 
diff --git a/package-lock.json b/package-lock.json
index cf1c991c..d18d6dee 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -7179,9 +7179,9 @@
       }
     },
     "node_modules/undici": {
-      "version": "7.28.0",
-      "resolved": "https://registry.npmjs.org/undici/-/undici-7.28.0.tgz",
-      "integrity": "sha512-cRZYrTDwWznlnRiPjggAGxZXanty6M8RV1ff8Wm4LWXBp7/IG8v5DnOm74DtUBp9OONpK75YlPnIjQqX0dBDtA==",
+      "version": "7.29.0",
+      "resolved": "https://registry.npmjs.org/undici/-/undici-7.29.0.tgz",
+      "integrity": "sha512-IDxfleLmmbSskfWSUATiN1nfn2rDuvnMOqb5CWR92iIfojA0Ud+ulOAAEQ57LPr9rWmsreUyf5lwyao+7GNNVw==",
       "dev": true,
       "license": "MIT",
       "engines": {