diff -r bd97eab25c70 Lib/http/cookies.py
--- a/Lib/http/cookies.py	Fri Nov 28 15:22:15 2014 -0800
+++ b/Lib/http/cookies.py	Mon Dec 01 18:20:37 2014 -0800
@@ -422,32 +422,49 @@
 #
 # Pattern for finding cookie
 #
-# This used to be strict parsing based on the RFC2109 and RFC2068
-# specifications.  I have since discovered that MSIE 3.0x doesn't
-# follow the character rules outlined in those specs.  As a
-# result, the parsing rules here are less strict.
+# Cookie values adhere to RFC 6265, which defines the grammar as:
 #
+# cookie-pair       = cookie-name "=" cookie-value
+# cookie-name       = token
+# cookie-value      = *cookie-octet / ( DQUOTE *cookie-octet DQUOTE )
+# cookie-octet      = %x21 / %x23-2B / %x2D-3A / %x3C-5B / %x5D-7E
+#                        ; US-ASCII characters excluding CTLs,
+#                        ; whitespace DQUOTE, comma, semicolon,
+#                        ; and backslash
+# token             = <token, defined in [RFC2616], Section 2.2>
 
-_LegalCharsPatt  = r"[\w\d!#%&'~_`><@,:/\$\*\+\-\.\^\|\)\(\?\}\{\=]"
+# RFC 2616, Section 2.2 defines a token as:
+#
+# token          = 1*<any CHAR except CTLs or separators>
+# separators     = "(" | ")" | "<" | ">" | "@"
+#                | "," | ";" | ":" | "\" | <">
+#                | "/" | "[" | "]" | "?" | "="
+#                | "{" | "}" | SP | HT
+
+# Note: ":" has been added to tokens to preserve backwards compatibility
+
+_LEGAL_TOKENS_PATT = r"[\w\d\*\+\-\.\$\|#%&'^_`~!:]"
+_LEGAL_VALUES_PATT = r"[\w\d\(\)\*\+\-\.\/\$\=\?\[\]\^\{\|\}!#%&':<>@_`~]"
+
 _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
-    )                              # End of group 'key'
-    (                              # Optional group: there may not be a value.
-    \s*=\s*                          # Equal Sign
-    (?P<val>                         # Start of group 'val'
-    "(?:[^\\"]|\\.)*"                  # Any doublequoted string
-    |                                  # or
+    (?x)                                    # This is a verbose pattern
+    \s*                                     # Optional whitespace at start of cookie
+    (?P<key>                                # Start of group 'key'
+    """ + _LEGAL_TOKENS_PATT + r"""+?       # Any word of at least one letter
+    )                                       # End of group 'key'
+    (                                       # Optional group: there may not be a value.
+    \s*=\s*                                 # Equal Sign
+    (?P<val>                                # Start of group 'val'
+    "(?:[^\\"]|\\.)*"                       # Any doublequoted string
+    |                                       # 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
-    )                                # End of group 'val'
-    )?                             # End of optional value group
-    \s*                            # Any number of spaces.
-    (\s+|;|$)                      # Ending either at space, semicolon, or EOS.
-    """, re.ASCII)                 # May be removed if safe.
+    |                                       # or
+    """ + _LEGAL_VALUES_PATT + r"""*        # Any word or empty string
+    )                                       # End of group 'val'
+    )?                                      # End of optional value group
+    \s*                                     # Any number of spaces.
+    (\s+|;|$)                               # Ending either at space, semicolon, or EOS.
+    """, re.ASCII)                          # May be removed if safe.
 
 
 # At long last, here is the cookie class.  Using this class is almost just like
diff -r bd97eab25c70 Lib/test/test_http_cookies.py
--- a/Lib/test/test_http_cookies.py	Fri Nov 28 15:22:15 2014 -0800
+++ b/Lib/test/test_http_cookies.py	Mon Dec 01 18:20:37 2014 -0800
@@ -35,6 +35,12 @@
              'repr': "<SimpleCookie: keebler='E=mc2'>",
              'output': 'Set-Cookie: keebler=E=mc2'},
 
+            # issue22931
+            {'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': 'Set-Cookie: a=b\nSet-Cookie: c=[\nSet-Cookie: d=r\nSet-Cookie: f=h'},
+
             # Cookies with ':' character in their name. Though not mentioned in
             # RFC, servers / browsers allow it.