From 724ae4d652417c4490a71ea0b16b8804dad3004f Mon Sep 17 00:00:00 2001
From: "patchback[bot]" <45432694+patchback[bot]@users.noreply.github.com>
Date: Sun, 7 Jun 2026 05:47:16 +0000
Subject: [PATCH] [PR #12831/1ac92dae backport][3.14] Payload close on
 disconnect (#12843)

CVE: CVE-2026-54280
Upstream-Status: Backport [https://github.com/aio-libs/aiohttp/commit/a762eda5242f6490d6ba667533193f8b473ad587]

Co-authored-by: J. Nick Koston <nick@koston.org>
(cherry picked from commit a762eda5242f6490d6ba667533193f8b473ad587)
Signed-off-by: Darsh Kelaiya <dkelaiya@cisco.com>
---
 CHANGES/12831.bugfix.rst   |  1 +
 aiohttp/web_response.py    |  6 ++--
 tests/test_web_response.py | 73 +++++++++++++++++++++++++++++++++++++-
 3 files changed, 77 insertions(+), 3 deletions(-)
 create mode 100644 CHANGES/12831.bugfix.rst

diff --git a/CHANGES/12831.bugfix.rst b/CHANGES/12831.bugfix.rst
new file mode 100644
index 000000000..bf460ffcc
--- /dev/null
+++ b/CHANGES/12831.bugfix.rst
@@ -0,0 +1 @@
+Fixed :meth:`aiohttp.web.Response.write_eof` skipping ``Payload.close()`` when the body write was interrupted by an error or cancellation, for example when a client disconnects mid-response; the payload close hook now runs in a ``finally`` so a :class:`~aiohttp.payload.Payload` body always releases its resources -- by :user:`bdraco`.
diff --git a/aiohttp/web_response.py b/aiohttp/web_response.py
index 364270e4d..cea5d4b45 100644
--- a/aiohttp/web_response.py
+++ b/aiohttp/web_response.py
@@ -779,8 +779,10 @@ class Response(StreamResponse):
         if body is None or self._must_be_empty_body:
             await super().write_eof()
         elif isinstance(self._body, Payload):
-            await self._body.write(self._payload_writer)
-            await self._body.close()
+            try:
+                await self._body.write(self._payload_writer)
+            finally:
+                await self._body.close()
             await super().write_eof()
         else:
             await super().write_eof(cast(bytes, body))
diff --git a/tests/test_web_response.py b/tests/test_web_response.py
index 5a4fb7e66..f094cd3d2 100644
--- a/tests/test_web_response.py
+++ b/tests/test_web_response.py
@@ -1,3 +1,4 @@
+import asyncio
 import collections.abc
 import datetime
 import gzip
@@ -18,7 +19,7 @@ from aiohttp.abc import AbstractStreamWriter
 from aiohttp.helpers import ETag
 from aiohttp.http_writer import StreamWriter, _serialize_headers
 from aiohttp.multipart import BodyPartReader, MultipartWriter
-from aiohttp.payload import BytesPayload, StringPayload
+from aiohttp.payload import BytesPayload, Payload, StringPayload
 from aiohttp.test_utils import make_mocked_request
 from aiohttp.web import ContentCoding, Response, StreamResponse, json_response
 
@@ -1370,6 +1371,76 @@ async def test_consecutive_write_eof() -> None:
     writer.write_eof.assert_called_once_with(data)
 
 
+class _ClosingPayload(Payload):
+    """Payload test double that records whether close() ran."""
+
+    def __init__(self) -> None:
+        super().__init__(None)
+        self.close_called = False
+        self.started = asyncio.Event()
+        self.release = asyncio.Event()
+        self.fail = False
+
+    async def write(self, writer: AbstractStreamWriter) -> None:
+        self.started.set()
+        if self.fail:
+            raise ConnectionResetError("client gone")
+        await self.release.wait()
+
+    async def close(self) -> None:
+        self.close_called = True
+        await super().close()
+
+    def decode(self, encoding: str = "utf-8", errors: str = "strict") -> str:
+        assert False
+
+
+async def test_write_eof_closes_payload_on_success() -> None:
+    writer = mock.create_autospec(AbstractStreamWriter, spec_set=True, instance=True)
+    req = make_request("GET", "/", writer=writer)
+    payload = _ClosingPayload()
+    payload.release.set()
+    resp = web.Response(body=payload)
+
+    await resp.prepare(req)
+    await resp.write_eof()
+
+    assert payload.close_called
+    assert writer.write_eof.called
+
+
+async def test_write_eof_closes_payload_on_write_error() -> None:
+    writer = mock.create_autospec(AbstractStreamWriter, spec_set=True, instance=True)
+    req = make_request("GET", "/", writer=writer)
+    payload = _ClosingPayload()
+    payload.fail = True
+    resp = web.Response(body=payload)
+
+    await resp.prepare(req)
+    with pytest.raises(ConnectionResetError):
+        await resp.write_eof()
+
+    assert payload.close_called
+    assert not writer.write_eof.called
+
+
+async def test_write_eof_closes_payload_on_cancel() -> None:
+    writer = mock.create_autospec(AbstractStreamWriter, spec_set=True, instance=True)
+    req = make_request("GET", "/", writer=writer)
+    payload = _ClosingPayload()
+    resp = web.Response(body=payload)
+
+    await resp.prepare(req)
+    task = asyncio.ensure_future(resp.write_eof())
+    await payload.started.wait()
+    task.cancel()
+    with pytest.raises(asyncio.CancelledError):
+        await task
+
+    assert payload.close_called
+    assert not writer.write_eof.called
+
+
 def test_set_text_with_content_type() -> None:
     resp = Response()
     resp.content_type = "text/html"