diff --git a/scripts/github/real-behavior-proof-policy.mjs b/scripts/github/real-behavior-proof-policy.mjs
index 14436d70bec9..2b5d6ffd52ef 100644
--- a/scripts/github/real-behavior-proof-policy.mjs
+++ b/scripts/github/real-behavior-proof-policy.mjs
@@ -134,6 +134,10 @@ export async function readBoundedGitHubApiJson(
   return JSON.parse(text);
 }
 
+async function cancelGitHubApiResponseBody(response) {
+  await response.body?.cancel?.().catch(() => undefined);
+}
+
 function normalizeLineEndings(text = "") {
   return text.replace(/\r\n?/g, "\n");
 }
@@ -193,21 +197,30 @@ export async function isMaintainerTeamMember({
         signal,
       }),
   );
-  if (response.status === 404) {
-    return false;
+  try {
+    if (response.status === 404) {
+      return false;
+    }
+    if (!response.ok) {
+      throw new Error(`Team membership lookup failed: ${response.status}`);
+    }
+    const body = await withGitHubApiTimeout(
+      `maintainer membership response for ${login}`,
+      timeoutMs,
+      (signal) =>
+        readBoundedGitHubApiJson(
+          response,
+          `maintainer membership response for ${login}`,
+          undefined,
+          {
+            signal,
+          },
+        ),
+    );
+    return body?.state === "active";
+  } finally {
+    await cancelGitHubApiResponseBody(response);
   }
-  if (!response.ok) {
-    throw new Error(`Team membership lookup failed: ${response.status}`);
-  }
-  const body = await withGitHubApiTimeout(
-    `maintainer membership response for ${login}`,
-    timeoutMs,
-    (signal) =>
-      readBoundedGitHubApiJson(response, `maintainer membership response for ${login}`, undefined, {
-        signal,
-      }),
-  );
-  return body?.state === "active";
 }
 
 function nextFenceMarker(line, fenceMarker) {
diff --git a/test/scripts/real-behavior-proof-policy.test.ts b/test/scripts/real-behavior-proof-policy.test.ts
index 35305bcca2db..5c7e7baffb93 100644
--- a/test/scripts/real-behavior-proof-policy.test.ts
+++ b/test/scripts/real-behavior-proof-policy.test.ts
@@ -560,6 +560,22 @@ describe("isMaintainerTeamMember", () => {
     expect(await isMaintainerTeamMember({ token: "t", org: "o", login: "u", fetch })).toBe(false);
   });
 
+  it("cancels 404 membership response bodies", async () => {
+    let canceled = false;
+    const response = new Response(
+      new ReadableStream<Uint8Array>({
+        cancel() {
+          canceled = true;
+        },
+      }),
+      { status: 404 },
+    );
+    const fetch = vi.fn().mockResolvedValue(response);
+
+    expect(await isMaintainerTeamMember({ token: "t", org: "o", login: "u", fetch })).toBe(false);
+    expect(canceled).toBe(true);
+  });
+
   it("returns false when the token, org, or login is missing", async () => {
     const fetch = vi.fn();
     expect(await isMaintainerTeamMember({ org: "o", login: "u", fetch })).toBe(false);
@@ -575,6 +591,24 @@ describe("isMaintainerTeamMember", () => {
     ).rejects.toThrow(/500/);
   });
 
+  it("cancels unexpected HTTP error response bodies", async () => {
+    let canceled = false;
+    const response = new Response(
+      new ReadableStream<Uint8Array>({
+        cancel() {
+          canceled = true;
+        },
+      }),
+      { status: 500 },
+    );
+    const fetch = vi.fn().mockResolvedValue(response);
+
+    await expect(
+      isMaintainerTeamMember({ token: "t", org: "o", login: "u", fetch }),
+    ).rejects.toThrow(/500/);
+    expect(canceled).toBe(true);
+  });
+
   it("aborts stalled membership fetches", async () => {
     const fetch = vi.fn((_url: string, init: RequestInit) => {
       return new Promise((_resolve, reject) => {