aaltat: Not good enough, order of keys will be random and causes inconsistency. 
pekkaklarck: I'd just use

     self.extra = extra

instead of adding separate attributes for all this non-standard info. Not sure should it even be listed in `__str__` either. Main problem at the moment is that this extra stuff breaks getting cookies. Nobody has told validating or even seeing this info is important.
aaltat: Good point and it sounds like a better idea. Although
aaltat: Didn't mean to close the PR.
diff --git a/src/SeleniumLibrary/keywords/cookie.py b/src/SeleniumLibrary/keywords/cookie.py
index 1f85948f..493b83b0 100644
--- a/src/SeleniumLibrary/keywords/cookie.py
+++ b/src/SeleniumLibrary/keywords/cookie.py
@@ -90,14 +90,22 @@ class CookieKeywords(LibraryComponent):
         | secure        | When true, cookie is only used with HTTPS connections.     |
         | httpOnly      | When true, cookie is not accessible via JavaScript.        |
         | expiry        | Python datetime object indicating when the cookie expires. |
+        | extra         | Possible attributes outside of the WebDriver specification |
 
         See the
-        [https://w3c.github.io/webdriver/webdriver-spec.html#cookies|WebDriver specification]
+        [https://w3c.github.io/webdriver/#cookies|WebDriver specification]
         for details about the cookie information.
         Notice that ``expiry`` is specified as a
         [https://docs.python.org/3/library/datetime.html#datetime.datetime|datetime object],
         not as seconds since Unix Epoch like WebDriver natively does.
 
+        In some cases, example when running browser in the cloud, it is possible that
+        cookie contains other attributes than is defined in the
+        [https://w3c.github.io/webdriver/#cookies|WebDriver specification].
+        These other attributes are available in a ``extra`` attribute in the cookie
+        object and it contains a dictionary of the other attributes. The ``extra``
+        attribute is new in SeleniumLibrary 4.0.
+
         Example:
         | `Add Cookie`      | foo             | bar |
         | ${cookie} =       | `Get Cookie`    | foo |
@@ -152,7 +160,7 @@ class CookieKeywords(LibraryComponent):
 class CookieInformation(object):
 
     def __init__(self, name, value, path=None, domain=None, secure=False,
-                 httpOnly=False, expiry=None):
+                 httpOnly=False, expiry=None, **extra):
         self.name = name
         self.value = value
         self.path = path
@@ -160,8 +168,12 @@ class CookieInformation(object):
         self.secure = secure
         self.httpOnly = httpOnly
         self.expiry = datetime.fromtimestamp(expiry) if expiry else None
+        self.extra = extra
 
     def __str__(self):
         items = 'name value path domain secure httpOnly expiry'.split()
-        return '\n'.join('%s=%s' % (item, getattr(self, item))
-                         for item in items)
+        string = '\n'.join('%s=%s' % (item, getattr(self, item))
+                           for item in items)
+        if self.extra:
+            string = '%s%s=%s\n' % (string, 'extra', self.extra)
+        return string

Get Cookies keyword will fail if the Selenium get_cookie method return value contains more keys than: name, value, path, domain, secure, httpOnly and expiry
Selenium [get_cookie](https://seleniumhq.github.io/selenium/docs/api/py/webdriver_remote/selenium.webdriver.remote.webdriver.html?highlight=get_cookie#selenium.webdriver.remote.webdriver.WebDriver.get_cookie) returns a dictionary. If the dictionary contains more keys then the `name`, `value`, `path`, `domain`, `secure`, `httpOnly` and `expiry`, then the Get Cookies keyword will fail:
```
20190212 16:54:43.113 :  FAIL : TypeError: __init__() got an unexpected keyword argument 'hCode'
20190212 16:54:43.113 : DEBUG :
Traceback (most recent call last):
  File "C:\Python27\lib\site-packages\SeleniumLibrary\__init__.py", line 369, in run_keyword
    return DynamicCore.run_keyword(self, name, args, kwargs)
  File "C:\Python27\lib\site-packages\SeleniumLibrary\base\robotlibcore.py", line 102, in run_keyword
    return self.keywords[name](*args, **kwargs)
  File "C:\Python27\lib\site-packages\SeleniumLibrary\keywords\cookie.py", line 99, in get_cookie
    return CookieInformation(**cookie)
```
This is because the Get Cookies keywords has hard coded keys what Selenium response [can contain in the CookieInformation](https://github.com/robotframework/SeleniumLibrary/blob/master/src/SeleniumLibrary/keywords/cookie.py#L152) object. The limitation has been in place since the SeleniumLibrary 3.0 release, but there was issue reported in Slack, that for that particular user, Selenium `get_cookie` did return the following:
```
{u'domain': u'1.2.3.4', u'name': u'components_state', u'value': u'alsdjaslkdjasdlkj', u'path': u'/', u'hCode': -1693023704, u'class': u'org.openqa.selenium.Cookie', u'httpOnly': False, u'secure': False}
```
SeleniumLibrary should not fail, if the Selenium `get_cookie`  returns more keys that [is specified ](https://w3c.github.io/webdriver/#dfn-table-for-cookie-conversion). Instead we should allow extra keys to be passed to the `CookieInformation` object and allow access to the extra keys in similar way as the specified keys. 
diff --git a/utest/test/keywords/test_cookie.py b/utest/test/keywords/test_cookie.py
index c85caaf9..3e951135 100644
--- a/utest/test/keywords/test_cookie.py
+++ b/utest/test/keywords/test_cookie.py
@@ -1,8 +1,10 @@
+from datetime import datetime
 import unittest
 
 from mockito import mock, unstub, verify
 
 from SeleniumLibrary.keywords import CookieKeywords
+from SeleniumLibrary.keywords.cookie import CookieInformation
 
 
 class KeywordArgumentsCookieTest(unittest.TestCase):
@@ -72,3 +74,41 @@ class KeywordArgumentsCookieTest(unittest.TestCase):
         self.cookie.add_cookie('name', 'value', path='None', domain=None,
                                secure=None)
         verify(self.driver).add_cookie(self.default_cookie)
+
+
+class CookieObjecttest(unittest.TestCase):
+
+    all_args = {'name': 'foo', 'value': '123', 'path': '/', 'domain': 'not.Here',
+                'secure': True, 'httpOnly': True, 'expiry': 123}
+
+    def test_name_value_only(self):
+        cookie = CookieInformation(name='foo', value='bar')
+        self.assertEqual(cookie.name, 'foo')
+        self.assertEqual(cookie.value, 'bar')
+
+    def test_all_args(self):
+        cookie = CookieInformation(**self.all_args)
+        self.assertEqual(cookie.name, 'foo')
+        self.assertEqual(cookie.value, '123')
+        self.assertEqual(cookie.path, '/')
+        self.assertEqual(cookie.domain, 'not.Here')
+        self.assertEqual(cookie.secure, True)
+        self.assertEqual(cookie.httpOnly, True)
+        self.assertEqual(cookie.expiry, datetime.fromtimestamp(123))
+        self.assertEqual(cookie.extra, {})
+
+    def test_extra_args(self):
+        cookie_dict = self.all_args.copy()
+        cookie_dict['class_name'] = 'seleniumLibary'
+        cookie = CookieInformation(**cookie_dict)
+        self.assertEqual(cookie.name, 'foo')
+        self.assertEqual(cookie.value, '123')
+        self.assertEqual(cookie.extra, {'class_name': 'seleniumLibary'})
+        string = str(cookie)
+        self.assertIn("extra={'class_name': 'seleniumLibary'}", string)
+
+    def test_no_mandatory_args(self):
+        cookie_dict = self.all_args.copy()
+        del cookie_dict['name']
+        with self.assertRaises(TypeError):
+            CookieInformation(**cookie_dict)

pip install -e .[dev]
parse_log_pytest
requirements.txt
pytest pytest-cov pytest-xdist pytest-mock pytest-asyncio mockito
apt-get update apt-get install -y gcc
3.9
requirements.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
attrs==25.3.0
certifi==2025.1.31
coverage==7.8.0
exceptiongroup==1.2.2
execnet==2.1.1
h11==0.14.0
idna==3.10
iniconfig==2.1.0
mockito==1.5.4
outcome==1.3.0.post0
packaging==24.2
pluggy==1.5.0
PySocks==1.7.1
pytest==8.3.5
pytest-asyncio==0.26.0
pytest-cov==6.0.0
pytest-mock==3.14.0
pytest-xdist==3.6.1
robotframework==7.2.2
-e git+https://github.com/robotframework/SeleniumLibrary.git@b504f1e0316ab6f1413d87477efe53b84d332cad#egg=robotframework_seleniumlibrary
selenium==4.30.0
sniffio==1.3.1
sortedcontainers==2.4.0
tomli==2.2.1
trio==0.29.0
trio-websocket==0.12.2
typing_extensions==4.13.0
urllib3==2.3.0
websocket-client==1.8.0
wsproto==1.2.0

name: SeleniumLibrary
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.4.4=h6a678d5_1
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=3.0.16=h5eee18b_0
  - pip=25.0=py39h06a4308_0
  - python=3.9.21=he870216_1
  - readline=8.2=h5eee18b_0
  - setuptools=75.8.0=py39h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - tzdata=2025a=h04d1e81_0
  - wheel=0.45.1=py39h06a4308_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - attrs==25.3.0
      - certifi==2025.1.31
      - coverage==7.8.0
      - exceptiongroup==1.2.2
      - execnet==2.1.1
      - h11==0.14.0
      - idna==3.10
      - iniconfig==2.1.0
      - mockito==1.5.4
      - outcome==1.3.0.post0
      - packaging==24.2
      - pluggy==1.5.0
      - pysocks==1.7.1
      - pytest==8.3.5
      - pytest-asyncio==0.26.0
      - pytest-cov==6.0.0
      - pytest-mock==3.14.0
      - pytest-xdist==3.6.1
      - robotframework==7.2.2
      - selenium==4.30.0
      - sniffio==1.3.1
      - sortedcontainers==2.4.0
      - tomli==2.2.1
      - trio==0.29.0
      - trio-websocket==0.12.2
      - typing-extensions==4.13.0
      - urllib3==2.3.0
      - websocket-client==1.8.0
      - wsproto==1.2.0
prefix: /opt/conda/envs/SeleniumLibrary

utest/test/keywords/test_cookie.py::CookieObjecttest::test_all_args utest/test/keywords/test_cookie.py::CookieObjecttest::test_extra_args
utest/test/keywords/test_cookie.py::KeywordArgumentsCookieTest::test_add_cookie_default utest/test/keywords/test_cookie.py::KeywordArgumentsCookieTest::test_add_cookie_domain_false utest/test/keywords/test_cookie.py::KeywordArgumentsCookieTest::test_add_cookie_domain_true utest/test/keywords/test_cookie.py::KeywordArgumentsCookieTest::test_add_cookie_path_false utest/test/keywords/test_cookie.py::KeywordArgumentsCookieTest::test_add_cookie_path_true utest/test/keywords/test_cookie.py::KeywordArgumentsCookieTest::test_add_cookie_secure_false utest/test/keywords/test_cookie.py::KeywordArgumentsCookieTest::test_add_cookie_secure_true utest/test/keywords/test_cookie.py::CookieObjecttest::test_name_value_only utest/test/keywords/test_cookie.py::CookieObjecttest::test_no_mandatory_args
src/SeleniumLibrary/keywords/cookie.py
src/SeleniumLibrary/keywords/cookie.py