CVE-2026-34993

@@ -4,6 +4,7 @@
 import datetime
 import heapq
 import itertools
+import json
 import os  # noqa
 import pathlib
 import pickle
@@ -38,6 +39,41 @@
 _SIMPLE_COOKIE = SimpleCookie()
 
 
+class _RestrictedCookieUnpickler(pickle.Unpickler):
+    """A restricted unpickler that only allows cookie-related types.
+
+    This prevents arbitrary code execution when loading pickled cookie data
+    from untrusted sources. Only types that are expected in a serialized
+    CookieJar are permitted.
+
+    See: https://docs.python.org/3/library/pickle.html#restricting-globals
+    """
+
+    _ALLOWED_CLASSES: frozenset[tuple[str, str]] = frozenset(
+        {
+            # Core cookie types
+            ("http.cookies", "SimpleCookie"),
+            ("http.cookies", "Morsel"),
+            # Container types used by CookieJar._cookies
+            ("collections", "defaultdict"),
+            # builtins that pickle uses for reconstruction
+            ("builtins", "tuple"),
+            ("builtins", "set"),
+            ("builtins", "frozenset"),
+            ("builtins", "dict"),
+        }
+    )
+
+    def find_class(self, module: str, name: str) -> type:
+        if (module, name) not in self._ALLOWED_CLASSES:
+            raise pickle.UnpicklingError(
+                f"Forbidden class: {module}.{name}. "
+                "CookieJar.load() only allows cookie-related types for security. "
+                "See https://docs.python.org/3/library/pickle.html#restricting-globals"
+            )
+        return super().find_class(module, name)  # type: ignore[no-any-return]
+
+
 class CookieJar(AbstractCookieJar):
     """Implements cookie storage adhering to RFC 6265."""
 
@@ -112,14 +148,84 @@ def quote_cookie(self) -> bool:
         return self._quote_cookie
 
     def save(self, file_path: PathLike) -> None:
+        """Save cookies to a file using JSON format.
+
+        :param file_path: Path to file where cookies will be serialized,
+            :class:`str` or :class:`pathlib.Path` instance.
+        """
         file_path = pathlib.Path(file_path)
-        with file_path.open(mode="wb") as f:
-            pickle.dump(self._cookies, f, pickle.HIGHEST_PROTOCOL)
+        data: dict[str, dict[str, dict[str, str | bool]]] = {}
+        for (domain, path), cookie in self._cookies.items():
+            key = f"{domain}|{path}"
+            data[key] = {}
+            for name, morsel in cookie.items():
+                morsel_data: dict[str, str | bool] = {
+                    "key": morsel.key,
+                    "value": morsel.value,
+                    "coded_value": morsel.coded_value,
+                }
+                # Save all morsel attributes that have values
+                for attr in morsel._reserved:  # type: ignore[attr-defined]
+                    attr_val = morsel[attr]
+                    if attr_val:
+                        morsel_data[attr] = attr_val
+                data[key][name] = morsel_data
+        with file_path.open(mode="w", encoding="utf-8") as f:
+            json.dump(data, f, indent=2)
 
     def load(self, file_path: PathLike) -> None:
+        """Load cookies from a file.
+
+        Tries to load JSON format first. Falls back to loading legacy
+        pickle format (using a restricted unpickler) for backward
+        compatibility with existing cookie files.
+
+        :param file_path: Path to file from where cookies will be
+            imported, :class:`str` or :class:`pathlib.Path` instance.
+        """
         file_path = pathlib.Path(file_path)
-        with file_path.open(mode="rb") as f:
-            self._cookies = pickle.load(f)
+        # Try JSON format first
+        try:
+            with file_path.open(mode="r", encoding="utf-8") as f:
+                data = json.load(f)
+            self._cookies = self._load_json_data(data)
+        except (json.JSONDecodeError, UnicodeDecodeError, ValueError):
+            # Fall back to legacy pickle format with restricted unpickler
+            with file_path.open(mode="rb") as f:
+                self._cookies = _RestrictedCookieUnpickler(f).load()
+
+    def _load_json_data(
+        self, data: dict[str, dict[str, dict[str, str | bool]]]
+    ) -> defaultdict[tuple[str, str], SimpleCookie]:
+        """Load cookies from parsed JSON data."""
+        cookies: defaultdict[tuple[str, str], SimpleCookie] = defaultdict(SimpleCookie)
+        for compound_key, cookie_data in data.items():
+            domain, path = compound_key.split("|", 1)
+            key = (domain, path)
+            for name, morsel_data in cookie_data.items():
+                morsel: Morsel[str] = Morsel()
+                morsel_key = morsel_data["key"]
+                morsel_value = morsel_data["value"]
+                morsel_coded_value = morsel_data["coded_value"]
+                # Use __setstate__ to bypass validation, same pattern
+                # used in _build_morsel and _cookie_helpers.
+                morsel.__setstate__(  # type: ignore[attr-defined]
+                    {
+                        "key": morsel_key,
+                        "value": morsel_value,
+                        "coded_value": morsel_coded_value,
+                    }
+                )
+                # Restore morsel attributes
+                for attr in morsel._reserved:  # type: ignore[attr-defined]
+                    if attr in morsel_data and attr not in (
+                        "key",
+                        "value",
+                        "coded_value",
+                    ):
+                        morsel[attr] = morsel_data[attr]
+                cookies[key][name] = morsel
+        return cookies
 
     def clear(self, predicate: ClearCookiePredicate | None = None) -> None:
         if predicate is None:

@@ -0,0 +1,6 @@
+Switched :py:meth:`~aiohttp.CookieJar.save` to use JSON format and
+:py:meth:`~aiohttp.CookieJar.load` to try JSON first with a fallback to
+a restricted pickle unpickler that only allows cookie-related types
+(``SimpleCookie``, ``Morsel``, ``defaultdict``, etc.), preventing
+arbitrary code execution via malicious pickle payloads
+(CWE-502) -- by :user:`YuvalElbar6`.

@@ -2496,16 +2496,28 @@ Utilities
 
    .. method:: save(file_path)
 
-      Write a pickled representation of cookies into the file
+      Write a JSON representation of cookies into the file
       at provided path.
 
+      .. versionchanged:: 3.14
+
+         Previously used pickle format. Now uses JSON for safe
+         serialization.
+
       :param file_path: Path to file where cookies will be serialized,
           :class:`str` or :class:`pathlib.Path` instance.
 
    .. method:: load(file_path)
 
-      Load a pickled representation of cookies from the file
-      at provided path.
+      Load cookies from the file at provided path. Tries JSON format
+      first, then falls back to legacy pickle format (using a restricted
+      unpickler that only allows cookie-related types) for backward
+      compatibility with existing cookie files.
+
+      .. versionchanged:: 3.14
+
+         Now loads JSON format by default. Falls back to restricted
+         pickle for files saved by older versions.
 
       :param file_path: Path to file from where cookies will be
            imported, :class:`str` or :class:`pathlib.Path` instance.

@@ -99,6 +99,7 @@ deduplicate
 defs
 Dependabot
 deprecations
+deserialization
 DER
 dev
 Dev
@@ -213,7 +214,8 @@ Multipart
 musllinux
 mypy
 Nagle
-Nagle’s
+Nagle's
+NFS
 namedtuple
 nameservers
 namespace
@@ -236,6 +238,7 @@ param
 params
 parsers
 pathlib
+payloads
 peername
 performant
 pickleable
@@ -356,6 +359,8 @@ unhandled
 unicode
 unittest
 Unittest
+unpickler
+untrusted
 unix
 unobvious
 unsets

@@ -95,6 +95,11 @@ def blockbuster(request: pytest.FixtureRequest) -> Iterator[None]:
             bb.functions[func].can_block_in(
                 "aiohttp/web_urldispatcher.py", "add_static"
             )
+        # save/load is not async, so we must allow this:
+        for func in ("io.TextIOWrapper.read", "io.BufferedReader.read"):
+            bb.functions[func].can_block_in("aiohttp/cookiejar.py", "load")
+        for func in ("io.TextIOWrapper.write", "io.BufferedWriter.write"):
+            bb.functions[func].can_block_in("aiohttp/cookiejar.py", "save")
         # Note: coverage.py uses locking internally which can cause false positives
         # in blockbuster when it instruments code. This is particularly problematic
         # on Windows where it can lead to flaky test failures.

@@ -9,6 +9,7 @@
 import unittest
 from http.cookies import BaseCookie, Morsel, SimpleCookie
 from operator import not_
+from pathlib import Path
 from unittest import mock
 
 import pytest
@@ -1620,3 +1621,191 @@ async def test_shared_cookie_with_multiple_domains() -> None:
     # Verify cache is reused efficiently
     assert ("", "") in jar._morsel_cache
     assert "universal" in jar._morsel_cache[("", "")]
+
+
+# === Security tests for restricted unpickler and JSON save/load ===
+
+
+async def test_load_rejects_malicious_pickle(tmp_path: Path) -> None:
+    """Verify CookieJar.load() blocks arbitrary code execution via pickle.
+
+    A crafted pickle payload using os.system (or any non-cookie class)
+    must be rejected by the restricted unpickler.
+    """
+    import os
+
+    file_path = tmp_path / "malicious.pkl"
+
+    class RCEPayload:
+        def __reduce__(self) -> tuple[object, ...]:
+            return (os.system, ("echo PWNED",))
+
+    with open(file_path, "wb") as f:
+        pickle.dump(RCEPayload(), f, pickle.HIGHEST_PROTOCOL)
+
+    jar = CookieJar()
+    with pytest.raises(pickle.UnpicklingError, match="Forbidden class"):
+        jar.load(file_path)
+
+
+async def test_load_rejects_eval_payload(tmp_path: Path) -> None:
+    """Verify CookieJar.load() blocks eval-based pickle payloads."""
+    file_path = tmp_path / "eval_payload.pkl"
+
+    class EvalPayload:
+        def __reduce__(self) -> tuple[object, ...]:
+            return (eval, ("__import__('os').system('echo PWNED')",))
+
+    with open(file_path, "wb") as f:
+        pickle.dump(EvalPayload(), f, pickle.HIGHEST_PROTOCOL)
+
+    jar = CookieJar()
+    with pytest.raises(pickle.UnpicklingError, match="Forbidden class"):
+        jar.load(file_path)
+
+
+async def test_load_rejects_subprocess_payload(tmp_path: Path) -> None:
+    """Verify CookieJar.load() blocks subprocess-based pickle payloads."""
+    import subprocess
+
+    file_path = tmp_path / "subprocess_payload.pkl"
+
+    class SubprocessPayload:
+        def __reduce__(self) -> tuple[object, ...]:
+            return (subprocess.call, (["echo", "PWNED"],))
+
+    with open(file_path, "wb") as f:
+        pickle.dump(SubprocessPayload(), f, pickle.HIGHEST_PROTOCOL)
+
+    jar = CookieJar()
+    with pytest.raises(pickle.UnpicklingError, match="Forbidden class"):
+        jar.load(file_path)
+
+
+async def test_load_falls_back_to_pickle(
+    tmp_path: Path,
+    cookies_to_receive: SimpleCookie,
+) -> None:
+    """Verify load() falls back to restricted pickle for legacy cookie files.
+
+    Existing cookie files saved with older versions of aiohttp used pickle.
+    load() should detect that the file is not JSON and fall back to the
+    restricted pickle unpickler for backward compatibility.
+    """
+    file_path = tmp_path / "legit.pkl"
+
+    # Write a legacy pickle file directly (as old aiohttp save() would)
+    jar_save = CookieJar()
+    jar_save.update_cookies(cookies_to_receive)
+    with file_path.open(mode="wb") as f:
+        pickle.dump(jar_save._cookies, f, pickle.HIGHEST_PROTOCOL)
+
+    jar_load = CookieJar()
+    jar_load.load(file_path=file_path)
+
+    jar_test = SimpleCookie()
+    for cookie in jar_load:
+        jar_test[cookie.key] = cookie
+
+    assert jar_test == cookies_to_receive
+
+
+async def test_save_load_json_roundtrip(
+    tmp_path: Path,
+    cookies_to_receive: SimpleCookie,
+) -> None:
+    """Verify save/load roundtrip preserves cookies via JSON format."""
+    file_path = tmp_path / "cookies.json"
+
+    jar_save = CookieJar()
+    jar_save.update_cookies(cookies_to_receive)
+    jar_save.save(file_path=file_path)
+
+    jar_load = CookieJar()
+    jar_load.load(file_path=file_path)
+
+    saved_cookies = SimpleCookie()
+    for cookie in jar_save:
+        saved_cookies[cookie.key] = cookie
+
+    loaded_cookies = SimpleCookie()
+    for cookie in jar_load:
+        loaded_cookies[cookie.key] = cookie
+
+    assert saved_cookies == loaded_cookies
+
+
+async def test_save_load_json_partitioned_cookies(tmp_path: Path) -> None:
+    """Verify save/load roundtrip works with partitioned cookies."""
+    file_path = tmp_path / "partitioned.json"
+
+    jar_save = CookieJar()
+    jar_save.update_cookies_from_headers(
+        ["session=cookie; Partitioned"], URL("https://example.com/")
+    )
+    jar_save.save(file_path=file_path)
+
+    jar_load = CookieJar()
+    jar_load.load(file_path=file_path)
+
+    # Compare individual cookie values (same approach as test_save_load_partitioned_cookies)
+    saved = list(jar_save)
+    loaded = list(jar_load)
+    assert len(saved) == len(loaded)
+    for s, lo in zip(saved, loaded):
+        assert s.key == lo.key
+        assert s.value == lo.value
+        assert s["domain"] == lo["domain"]
+        assert s["path"] == lo["path"]
+
+
+async def test_json_format_is_safe(tmp_path: Path) -> None:
+    """Verify the JSON file format cannot execute code on load."""
+    import json
+
+    file_path = tmp_path / "safe.json"
+
+    # Write something that might look dangerous but is just data
+    malicious_data = {
+        "evil.com|/": {
+            "session": {
+                "key": "session",
+                "value": "__import__('os').system('echo PWNED')",
+                "coded_value": "__import__('os').system('echo PWNED')",
+            }
+        }
+    }
+    with open(file_path, "w") as f:
+        json.dump(malicious_data, f)
+
+    jar = CookieJar()
+    jar.load(file_path=file_path)
+
+    # The "malicious" string is just a cookie value, not executed code
+    cookies = list(jar)
+    assert len(cookies) == 1
+    assert cookies[0].value == "__import__('os').system('echo PWNED')"
+
+
+async def test_save_load_json_secure_cookies(tmp_path: Path) -> None:
+    """Verify save/load preserves Secure and HttpOnly flags."""
+    file_path = tmp_path / "secure.json"
+
+    jar_save = CookieJar()
+    jar_save.update_cookies_from_headers(
+        ["token=abc123; Secure; HttpOnly; Path=/; Domain=example.com"],
+        URL("https://example.com/"),
+    )
+    jar_save.save(file_path=file_path)
+
+    jar_load = CookieJar()
+    jar_load.load(file_path=file_path)
+
+    loaded_cookies = list(jar_load)
+    assert len(loaded_cookies) == 1
+    cookie = loaded_cookies[0]
+    assert cookie.key == "token"
+    assert cookie.value == "abc123"
+    assert cookie["secure"] is True
+    assert cookie["httponly"] is True
+    assert cookie["domain"] == "example.com"