diff --git a/scripts/e2e/kitchen-sink-rpc-walk.mjs b/scripts/e2e/kitchen-sink-rpc-walk.mjs
index 37190651820f..8ad3ea41c02e 100644
--- a/scripts/e2e/kitchen-sink-rpc-walk.mjs
+++ b/scripts/e2e/kitchen-sink-rpc-walk.mjs
@@ -980,7 +980,7 @@ export async function readBoundedResponseText(response, byteLimit, timeoutPromis
   const contentLength = response.headers?.get?.("content-length");
   if (contentLength && /^\d+$/u.test(contentLength)) {
     const parsedContentLength = Number(contentLength);
-    if (Number.isSafeInteger(parsedContentLength) && parsedContentLength > resolvedByteLimit) {
+    if (!Number.isSafeInteger(parsedContentLength) || parsedContentLength > resolvedByteLimit) {
       await response.body?.cancel?.().catch(() => undefined);
       throw createFetchBodyTooLargeError(resolvedByteLimit);
     }
diff --git a/test/scripts/kitchen-sink-rpc-walk.test.ts b/test/scripts/kitchen-sink-rpc-walk.test.ts
index 17d6ec3f16d2..8b763874d374 100644
--- a/test/scripts/kitchen-sink-rpc-walk.test.ts
+++ b/test/scripts/kitchen-sink-rpc-walk.test.ts
@@ -1923,6 +1923,21 @@ describe("kitchen-sink RPC process sampling", () => {
     expect(response.text).not.toHaveBeenCalled();
   });
 
+  it("rejects unsafe decimal HTTP content lengths before reading", async () => {
+    const response = {
+      headers: new Headers({
+        "content-length": "9007199254740992",
+      }),
+      text: vi.fn(async () => "not read"),
+    };
+
+    await expect(readBoundedResponseText(response, 1024)).rejects.toMatchObject({
+      code: "ETOOBIG",
+      message: "fetch response body exceeded 1024 bytes",
+    });
+    expect(response.text).not.toHaveBeenCalled();
+  });
+
   it("streams HTTP probe responses with non-decimal content-length values", async () => {
     let readStarted = false;
     let canceled = false;