diff --git a/Lib/test/test_urllib2.py b/Lib/test/test_urllib2.py
index 3d80e01..911a0af 100644
--- a/Lib/test/test_urllib2.py
+++ b/Lib/test/test_urllib2.py
@@ -1218,6 +1218,21 @@
     def test_basic_auth_with_single_quoted_realm(self):
         self.test_basic_auth(quote_char="'")
 
+    def test_basic_auth_with_unquoted_realm(self):
+        opener = OpenerDirector()
+        password_manager = MockPasswordManager()
+        auth_handler = urllib.request.HTTPBasicAuthHandler(password_manager)
+        realm = "ACME Widget Store"
+        http_handler = MockHTTPHandler(
+            401, 'WWW-Authenticate: Basic realm=%s\r\n\r\n' % realm)
+        opener.add_handler(auth_handler)
+        opener.add_handler(http_handler)
+        self._test_basic_auth(opener, auth_handler, "Authorization",
+                              realm, http_handler, password_manager,
+                              "http://acme.example.com/protected",
+                              "http://acme.example.com/protected",
+                              )
+
     def test_proxy_basic_auth(self):
         opener = OpenerDirector()
         ph = urllib.request.ProxyHandler(dict(http="proxy.example.com:3128"))
diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
index fe2cfcd..cbcbe1a 100644
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -794,7 +794,7 @@
     # allow for double- and single-quoted realm values
     # (single quotes are a violation of the RFC, but appear in the wild)
     rx = re.compile('(?:.*,)*[ \t]*([^ \t]+)[ \t]+'
-                    'realm=(["\'])(.*?)\\2', re.I)
+                    'realm=(["\']?)([^"\']*)\\2', re.I)
 
     # XXX could pre-emptively send auth info already accepted (RFC 2617,
     # end of section 2, and section 1.2 immediately after "credentials"
diff --git a/Misc/NEWS b/Misc/NEWS
index 10b5453..f3b14b3 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -63,6 +63,9 @@
 Library
 -------
 
+- Issue #12541: Be lenient with quotes around Realm field of HTTP Basic
+  Authentation in urllib2.
+
 - Issue #14662: Prevent shutil failures on OS X when destination does not
   support chflag operations.  Patch by Hynek Schlawack.