diff --git a/Lib/http/cookies.py b/Lib/http/cookies.py
index 556d101fb0e..00082a6740f 100644
--- a/Lib/http/cookies.py
+++ b/Lib/http/cookies.py
@@ -428,12 +428,13 @@ def OutputString(self, attrs=None):
 # result, the parsing rules here are less strict.
 #
 
-_LegalCharsPatt  = r"[\w\d!#%&'~_`><@,:/\$\*\+\-\.\^\|\)\(\?\}\{\=]"
+_LegalKeyChars  = r"\w\d!#%&'~_`><@,:/\$\*\+\-\.\^\|\)\(\?\}\{\="
+_LegalValueChars = _LegalKeyChars + '\[\]'
 _CookiePattern = re.compile(r"""
     (?x)                           # This is a verbose pattern
     \s*                            # Optional whitespace at start of cookie
     (?P<key>                       # Start of group 'key'
-    """ + _LegalCharsPatt + r"""+?   # Any word of at least one letter
+    [""" + _LegalKeyChars + r"""]+?   # Any word of at least one letter
     )                              # End of group 'key'
     (                              # Optional group: there may not be a value.
     \s*=\s*                          # Equal Sign
@@ -442,7 +443,7 @@ def OutputString(self, attrs=None):
     |                                  # or
     \w{3},\s[\w\d\s-]{9,11}\s[\d:]{8}\sGMT  # Special case for "expires" attr
     |                                  # or
-    """ + _LegalCharsPatt + r"""*      # Any word or empty string
+    [""" + _LegalValueChars + r"""]*      # Any word or empty string
     )                                # End of group 'val'
     )?                             # End of optional value group
     \s*                            # Any number of spaces.
diff --git a/Lib/test/test_http_cookies.py b/Lib/test/test_http_cookies.py
index 76e5e9c4dad..8d7c220c5b6 100644
--- a/Lib/test/test_http_cookies.py
+++ b/Lib/test/test_http_cookies.py
@@ -43,6 +43,19 @@ def test_basic(self):
              'repr': "<SimpleCookie: key:term='value:term'>",
              'output': 'Set-Cookie: key:term=value:term'},
 
+            # issue22931 - Adding '[' and ']' as valid characters in cookie
+            # values as defined in RFC 6265
+            {
+                'data': 'a=b; c=[; d=r; f=h',
+                'dict': {'a':'b', 'c':'[', 'd':'r', 'f':'h'},
+                'repr': "<SimpleCookie: a='b' c='[' d='r' f='h'>",
+                'output': '\n'.join((
+                    'Set-Cookie: a=b',
+                    'Set-Cookie: c=[',
+                    'Set-Cookie: d=r',
+                    'Set-Cookie: f=h'
+                ))
+            }
         ]
 
         for case in cases:
diff --git a/Misc/NEWS b/Misc/NEWS
index 827d761bf9f..0f969207d43 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -22,6 +22,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #22931: Allow '[' and ']' in cookie values.
+
 - Issue #24094: Fix possible crash in json.encode with poorly behaved dict
   subclasses.