diff --git a/src/auth/security.ts b/src/auth/security.ts
index d1fc0f059c..709ddcfb2b 100644
--- a/src/auth/security.ts
+++ b/src/auth/security.ts
@@ -119,7 +119,12 @@ export async function authenticatePrivateToken(env: Env, token: string | undefin
 }
 
 export async function authenticateInternalToken(env: Env, token: string | undefined): Promise<AuthIdentity | null> {
-  if (await timingSafeEqual(token, env.INTERNAL_JOB_TOKEN)) return { kind: "static", actor: "internal" };
+  // Mirror authenticatePrivateToken's normalization (#9713): early-exit on a falsy bearer, and compare against the
+  // trimmed secret via nonBlank(). extractBearerToken already trims the incoming token, so an INTERNAL_JOB_TOKEN
+  // secret carrying a trailing newline (the shape a `wrangler secret put` piped from a file produces) would
+  // otherwise never match any caller and 401 every /v1/internal/* route, unlike the three secrets above.
+  if (!token) return null;
+  if (await timingSafeEqual(token, nonBlank(env.INTERNAL_JOB_TOKEN))) return { kind: "static", actor: "internal" };
   return null;
 }
 
diff --git a/test/unit/auth-security-helpers.test.ts b/test/unit/auth-security-helpers.test.ts
index 50e7c8b88a..accc3a518b 100644
--- a/test/unit/auth-security-helpers.test.ts
+++ b/test/unit/auth-security-helpers.test.ts
@@ -1,6 +1,7 @@
 import { describe, expect, it } from "vitest";
 
 import {
+  authenticateInternalToken,
   buildBrowserSessionCookie,
   buildClearedBrowserSessionCookie,
   buildClearedGitHubOAuthStateCookie,
@@ -136,3 +137,36 @@ describe("session/oauth cookie builders", () => {
     );
   });
 });
+
+describe("authenticateInternalToken (#9713)", () => {
+  // authenticateInternalToken reads only env.INTERNAL_JOB_TOKEN, so a minimal cast keeps this pure-helper
+  // suite dependency-light (no D1) while still exercising both the nonBlank() and the early-exit branches.
+  const envWith = (internalJobToken: string): Env => ({ INTERNAL_JOB_TOKEN: internalJobToken }) as unknown as Env;
+
+  it("trims surrounding whitespace on INTERNAL_JOB_TOKEN, matching the three private secrets (regression for #9713)", async () => {
+    const env = envWith("  secret  ");
+    await expect(authenticateInternalToken(env, "secret")).resolves.toEqual({ kind: "static", actor: "internal" });
+  });
+
+  it("authenticates a correct, untrimmed secret (bearer already trimmed by extractBearerToken)", async () => {
+    const env = envWith("secret");
+    await expect(authenticateInternalToken(env, "secret")).resolves.toEqual({ kind: "static", actor: "internal" });
+  });
+
+  it("authenticates nobody when INTERNAL_JOB_TOKEN is whitespace-only", async () => {
+    const env = envWith("   ");
+    // The blank secret trims to undefined via nonBlank(), so even the same whitespace never matches.
+    await expect(authenticateInternalToken(env, "   ")).resolves.toBeNull();
+    await expect(authenticateInternalToken(env, "")).resolves.toBeNull();
+  });
+
+  it("early-returns null for an absent bearer without consulting the secret", async () => {
+    const env = envWith("secret");
+    await expect(authenticateInternalToken(env, undefined)).resolves.toBeNull();
+  });
+
+  it("rejects a token that does not match the configured secret", async () => {
+    const env = envWith("secret");
+    await expect(authenticateInternalToken(env, "wrong")).resolves.toBeNull();
+  });
+});