CVE-2026-34516

@@ -41,6 +41,7 @@
 )
 from .helpers import CHAR, TOKEN, parse_mimetype, reify
 from .http import HeadersParser
+from .http_exceptions import BadHttpMessage
 from .log import internal_logger
 from .payload import (
     JsonPayload,
@@ -658,7 +659,14 @@ class MultipartReader:
     #: Body part reader class for non multipart/* content types.
     part_reader_cls = BodyPartReader
 
-    def __init__(self, headers: Mapping[str, str], content: StreamReader) -> None:
+    def __init__(
+        self,
+        headers: Mapping[str, str],
+        content: StreamReader,
+        *,
+        max_field_size: int = 8190,
+        max_headers: int = 128,
+    ) -> None:
         self._mimetype = parse_mimetype(headers[CONTENT_TYPE])
         assert self._mimetype.type == "multipart", "multipart/* content type expected"
         if "boundary" not in self._mimetype.parameters:
@@ -669,8 +677,10 @@ def __init__(self, headers: Mapping[str, str], content: StreamReader) -> None:
         self.headers = headers
         self._boundary = ("--" + self._get_boundary()).encode()
         self._content = content
-        self._default_charset: Optional[str] = None
-        self._last_part: Optional[Union["MultipartReader", BodyPartReader]] = None
+        self._default_charset: str | None = None
+        self._last_part: MultipartReader | BodyPartReader | None = None
+        self._max_field_size = max_field_size
+        self._max_headers = max_headers
         self._at_eof = False
         self._at_bof = True
         self._unread: List[bytes] = []
@@ -770,7 +780,12 @@ def _get_part_reader(
         if mimetype.type == "multipart":
             if self.multipart_reader_cls is None:
                 return type(self)(headers, self._content)
-            return self.multipart_reader_cls(headers, self._content)
+            return self.multipart_reader_cls(
+                headers,
+                self._content,
+                max_field_size=self._max_field_size,
+                max_headers=self._max_headers,
+            )
         else:
             return self.part_reader_cls(
                 self._boundary,
@@ -832,12 +847,14 @@ async def _read_boundary(self) -> None:
     async def _read_headers(self) -> "CIMultiDictProxy[str]":
         lines = []
         while True:
-            chunk = await self._content.readline()
+            chunk = await self._content.readline(max_line_length=self._max_field_size)
             chunk = chunk.rstrip(b"\r\n")
             lines.append(chunk)
             if not chunk:
                 break
-        parser = HeadersParser()
+            if len(lines) > self._max_headers:
+                raise BadHttpMessage("Too many headers received")
+        parser = HeadersParser(max_field_size=self._max_field_size)
         headers, raw_headers = parser.parse_headers(lines)
         return headers
 

@@ -21,6 +21,7 @@
     set_exception,
     set_result,
 )
+from .http_exceptions import LineTooLong
 from .log import internal_logger
 
 __all__ = (
@@ -372,10 +373,12 @@ async def _wait(self, func_name: str) -> None:
         finally:
             self._waiter = None
 
-    async def readline(self) -> bytes:
-        return await self.readuntil()
+    async def readline(self, *, max_line_length: Optional[int] = None) -> bytes:
+        return await self.readuntil(max_size=max_line_length)
 
-    async def readuntil(self, separator: bytes = b"\n") -> bytes:
+    async def readuntil(
+        self, separator: bytes = b"\n", *, max_size: Optional[int] = None
+    ) -> bytes:
         seplen = len(separator)
         if seplen == 0:
             raise ValueError("Separator should be at least one-byte string")
@@ -386,6 +389,7 @@ async def readuntil(self, separator: bytes = b"\n") -> bytes:
         chunk = b""
         chunk_size = 0
         not_enough = True
+        max_size = max_size or self._high_water
 
         while not_enough:
             while self._buffer and not_enough:
@@ -400,8 +404,8 @@ async def readuntil(self, separator: bytes = b"\n") -> bytes:
                 if ichar:
                     not_enough = False
 
-                if chunk_size > self._high_water:
-                    raise ValueError("Chunk too big")
+                if chunk_size > max_size:
+                    raise LineTooLong(chunk[:100] + b"...", max_size)
 
             if self._eof:
                 break
@@ -622,7 +626,7 @@ async def wait_eof(self) -> None:
     def feed_data(self, data: bytes, n: int = 0) -> None:
         pass
 
-    async def readline(self) -> bytes:
+    async def readline(self, *, max_line_length: Optional[int] = None) -> bytes:
         return b""
 
     async def read(self, n: int = -1) -> bytes:

@@ -729,6 +729,9 @@ def make_mocked_request(
 
     if protocol is sentinel:
         protocol = mock.Mock()
+        protocol.max_field_size = 8190
+        protocol.max_line_length = 8190
+        protocol.max_headers = 128
         protocol.transport = transport
         type(protocol).peername = mock.PropertyMock(
             return_value=transport.get_extra_info("peername")

@@ -142,6 +142,9 @@ class RequestHandler(BaseProtocol):
     """
 
     __slots__ = (
+        "max_field_size",
+        "max_headers",
+        "max_line_size",
         "_request_count",
         "_keepalive",
         "_manager",
@@ -205,6 +208,10 @@ def __init__(
         self._request_handler: Optional[_RequestHandler] = manager.request_handler
         self._request_factory: Optional[_RequestFactory] = manager.request_factory
 
+        self.max_line_size = max_line_size
+        self.max_headers = max_headers
+        self.max_field_size = max_field_size
+
         self._tcp_keepalive = tcp_keepalive
         # placeholder to be replaced on keepalive timeout setup
         self._next_keepalive_close_time = 0.0

@@ -696,7 +696,12 @@ async def json(self, *, loads: JSONDecoder = DEFAULT_JSON_DECODER) -> Any:
 
     async def multipart(self) -> MultipartReader:
         """Return async iterator to process BODY as multipart."""
-        return MultipartReader(self._headers, self._payload)
+        return MultipartReader(
+            self._headers,
+            self._payload,
+            max_field_size=self._protocol.max_field_size,
+            max_headers=self._protocol.max_headers,
+        )
 
     async def post(self) -> "MultiDictProxy[Union[str, bytes, FileField]]":
         """Return POST parameters."""

@@ -3,6 +3,7 @@
 import json
 import pathlib
 import sys
+from typing import Optional
 from unittest import mock
 
 import pytest
@@ -85,7 +86,7 @@ async def read(self, size=None):
     def at_eof(self):
         return self.content.tell() == len(self.content.getbuffer())
 
-    async def readline(self):
+    async def readline(self, *, max_line_length: Optional[int] = None) -> bytes:
         return self.content.readline()
 
     def unread_data(self, data):
@@ -856,7 +857,7 @@ async def read(self, size=None) -> bytes:
             def at_eof(self) -> bool:
                 return not self.content
 
-            async def readline(self) -> bytes:
+            async def readline(self, *, max_line_length: int | None = None) -> bytes:
                 line = b""
                 while self.content and b"\n" not in line:
                     line += self.content.pop(0)

@@ -12,6 +12,7 @@
 from re_assert import Matches
 
 from aiohttp import streams
+from aiohttp.http_exceptions import LineTooLong
 
 DATA = b"line1\nline2\nline3\n"
 
@@ -325,7 +326,7 @@ async def test_readline_limit_with_existing_data(self) -> None:
         stream.feed_data(b"li")
         stream.feed_data(b"ne1\nline2\n")
 
-        with pytest.raises(ValueError):
+        with pytest.raises(LineTooLong):
             await stream.readline()
         # The buffer should contain the remaining data after exception
         stream.feed_eof()
@@ -346,7 +347,7 @@ def cb():
 
         loop.call_soon(cb)
 
-        with pytest.raises(ValueError):
+        with pytest.raises(LineTooLong):
             await stream.readline()
         data = await stream.read()
         assert b"chunk3\n" == data
@@ -436,7 +437,7 @@ async def test_readuntil_limit_with_existing_data(self, separator: bytes) -> Non
         stream.feed_data(b"li")
         stream.feed_data(b"ne1" + separator + b"line2" + separator)
 
-        with pytest.raises(ValueError):
+        with pytest.raises(LineTooLong):
             await stream.readuntil(separator)
         # The buffer should contain the remaining data after exception
         stream.feed_eof()
@@ -458,7 +459,7 @@ def cb():
 
         loop.call_soon(cb)
 
-        with pytest.raises(ValueError, match="Chunk too big"):
+        with pytest.raises(LineTooLong):
             await stream.readuntil(separator)
         data = await stream.read()
         assert b"chunk3#" == data

@@ -13,6 +13,7 @@
 
 from aiohttp import HttpVersion
 from aiohttp.base_protocol import BaseProtocol
+from aiohttp.http_exceptions import BadHttpMessage, LineTooLong
 from aiohttp.http_parser import RawRequestMessage
 from aiohttp.streams import StreamReader
 from aiohttp.test_utils import make_mocked_request
@@ -896,7 +897,57 @@ async def test_multipart_formdata_file(protocol: BaseProtocol) -> None:
     result["a_file"].file.close()
 
 
-async def test_make_too_big_request_limit_None(protocol) -> None:
+async def test_multipart_formdata_headers_too_many(protocol: BaseProtocol) -> None:
+    many = b"".join(f"X-{i}: a\r\n".encode() for i in range(130))
+    body = (
+        b"--b\r\n"
+        b'Content-Disposition: form-data; name="a"\r\n' + many + b"\r\n1\r\n"
+        b"--b--\r\n"
+    )
+    content_type = "multipart/form-data; boundary=b"
+    payload = StreamReader(protocol, 2**16, loop=asyncio.get_running_loop())
+    payload.feed_data(body)
+    payload.feed_eof()
+    req = make_mocked_request(
+        "POST",
+        "/",
+        headers={"CONTENT-TYPE": content_type},
+        payload=payload,
+    )
+
+    with pytest.raises(BadHttpMessage, match="Too many headers received"):
+        await req.post()
+
+
+async def test_multipart_formdata_header_too_long(protocol: BaseProtocol) -> None:
+    k = b"t" * 4100
+    body = (
+        b"--b\r\n"
+        b'Content-Disposition: form-data; name="a"\r\n'
+        + k
+        + b":"
+        + k
+        + b"\r\n"
+        + b"\r\n1\r\n"
+        b"--b--\r\n"
+    )
+    content_type = "multipart/form-data; boundary=b"
+    payload = StreamReader(protocol, 2**16, loop=asyncio.get_running_loop())
+    payload.feed_data(body)
+    payload.feed_eof()
+    req = make_mocked_request(
+        "POST",
+        "/",
+        headers={"CONTENT-TYPE": content_type},
+        payload=payload,
+    )
+
+    match = "400, message:\n  Got more than 8190 bytes when reading"
+    with pytest.raises(LineTooLong, match=match):
+        await req.post()
+
+
+async def test_make_too_big_request_limit_None(protocol: BaseProtocol) -> None:
     payload = StreamReader(protocol, 2**16, loop=asyncio.get_event_loop())
     large_file = 1024**2 * b"x"
     too_large_file = large_file + b"x"