diff --git a/Doc/library/http.cookiejar.rst b/Doc/library/http.cookiejar.rst
index 23ddecf873876d..3042e42c8cec23 100644
--- a/Doc/library/http.cookiejar.rst
+++ b/Doc/library/http.cookiejar.rst
@@ -84,7 +84,7 @@ The following classes are provided:
    from / returned to the server.
 
 
-.. class:: DefaultCookiePolicy( blocked_domains=None, allowed_domains=None, netscape=True, rfc2965=False, rfc2109_as_netscape=None, hide_cookie2=False, strict_domain=False, strict_rfc2965_unverifiable=True, strict_ns_unverifiable=False, strict_ns_domain=DefaultCookiePolicy.DomainLiberal, strict_ns_set_initial_dollar=False, strict_ns_set_path=False, secure_protocols=("https", "wss") )
+.. class:: DefaultCookiePolicy( blocked_domains=None, allowed_domains=None, netscape=True, rfc2965=False, rfc2109_as_netscape=None, hide_cookie2=False, strict_domain=False, strict_rfc2965_unverifiable=True, strict_ns_unverifiable=False, strict_ns_domain=DefaultCookiePolicy.DomainLiberal, strict_ns_set_initial_dollar=False, strict_ns_set_path=False, secure_protocols=("https", "wss"), additional_country_code_slds={} )
 
    Constructor arguments should be passed as keyword arguments only.
    *blocked_domains* is a sequence of domain names that we never accept cookies
@@ -92,8 +92,9 @@ The following classes are provided:
    sequence of the only domains for which we accept and return cookies.
    *secure_protocols* is a sequence of protocols for which secure cookies can be
    added to. By default *https* and *wss* (secure websocket) are considered
-   secure protocols. For all other arguments, see the documentation for
-   :class:`CookiePolicy` and :class:`DefaultCookiePolicy` objects.
+   secure protocols. *additional_country_code_slds* is a set of user-customized
+   additional country code second-level domains. For all other arguments, see the
+   documentation for :class:`CookiePolicy` and :class:`DefaultCookiePolicy` objects.
 
    :class:`DefaultCookiePolicy` implements the standard accept / reject rules for
    Netscape and :rfc:`2965` cookies.  By default, :rfc:`2109` cookies (ie. cookies
diff --git a/Lib/http/cookiejar.py b/Lib/http/cookiejar.py
index 68cf16c93cc1c8..3f7ad156b44a22 100644
--- a/Lib/http/cookiejar.py
+++ b/Lib/http/cookiejar.py
@@ -893,7 +893,8 @@ def __init__(self,
                  strict_ns_domain=DomainLiberal,
                  strict_ns_set_initial_dollar=False,
                  strict_ns_set_path=False,
-                 secure_protocols=("https", "wss")
+                 secure_protocols=("https", "wss"),
+                 additional_country_code_slds=set(),
                  ):
         """Constructor arguments should be passed as keyword arguments only."""
         self.netscape = netscape
@@ -907,6 +908,16 @@ def __init__(self,
         self.strict_ns_set_initial_dollar = strict_ns_set_initial_dollar
         self.strict_ns_set_path = strict_ns_set_path
         self.secure_protocols = secure_protocols
+        # source: https://en.wikipedia.org/wiki/Second-level_domain
+        well_known_slds = set(["co", "ac", "com", "edu", "org", "net",
+                        "gov", "mil", "int", "aero", "biz", "cat", "coop",
+                        "info", "jobs", "mobi", "museum", "name", "pro",
+                        "travel", "eu", "tv", "or", "nom", "sch", "web"])
+        if isinstance(additional_country_code_slds, set):
+            self.slds = well_known_slds.union(additional_country_code_slds)
+            _debug(f"The set of country code slds is {self.slds}")
+        else:
+            raise TypeError("attribute 'additional_country_code_slds' should be a 'set' type")
 
         if blocked_domains is not None:
             self._blocked_domains = tuple(blocked_domains)
@@ -1032,10 +1043,7 @@ def set_ok_domain(self, cookie, request):
                 if j == 0:  # domain like .foo.bar
                     tld = domain[i+1:]
                     sld = domain[j+1:i]
-                    if sld.lower() in ("co", "ac", "com", "edu", "org", "net",
-                       "gov", "mil", "int", "aero", "biz", "cat", "coop",
-                       "info", "jobs", "mobi", "museum", "name", "pro",
-                       "travel", "eu") and len(tld) == 2:
+                    if sld.lower() in self.slds and len(tld) == 2:
                         # domain like .co.uk
                         _debug("   country-code second level domain %s", domain)
                         return False
diff --git a/Misc/NEWS.d/next/Library/2025-06-16-15-31-22.gh-issue-135567.XnZIq7.rst b/Misc/NEWS.d/next/Library/2025-06-16-15-31-22.gh-issue-135567.XnZIq7.rst
new file mode 100644
index 00000000000000..a09ea9a4d07c09
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-06-16-15-31-22.gh-issue-135567.XnZIq7.rst
@@ -0,0 +1 @@
+:mod:`http.cookiejar`: add new attribute additional_country_code_slds in DefaultPolicy to support customization in country code second-level domains and add "tv", "or", "nom", "sch", and "web" to the default list of supported country code second-level domains.