diff --git a/build/controllers/ReleaseController.php b/build/controllers/ReleaseController.php
index 2b372cd842..d839885270 100644
--- a/build/controllers/ReleaseController.php
+++ b/build/controllers/ReleaseController.php
@@ -990,7 +990,7 @@ class ReleaseController extends Controller
     protected function updateYiiVersion($frameworkPath, $version)
     {
         $this->sed(
-            '/function getVersion\(\)\R    \{\R        return \'(.+?)\';/',
+            '/function getVersion\(\)\R {4}\{\R {8}return \'(.+?)\';/',
             "function getVersion()\n    {\n        return '$version';",
             $frameworkPath . '/BaseYii.php');
     }
diff --git a/framework/console/Controller.php b/framework/console/Controller.php
index 8964d6675a..614241d0f3 100644
--- a/framework/console/Controller.php
+++ b/framework/console/Controller.php
@@ -701,7 +701,7 @@ class Controller extends \yii\base\Controller
     protected function parseDocCommentTags($reflection)
     {
         $comment = $reflection->getDocComment();
-        $comment = "@description \n" . strtr(trim(preg_replace('/^\s*\**( |\t)?/m', '', trim($comment, '/'))), "\r", '');
+        $comment = "@description \n" . strtr(trim(preg_replace('/^\s*\**([ \t])?/m', '', trim($comment, '/'))), "\r", '');
         $parts = preg_split('/^\s*@/m', $comment, -1, PREG_SPLIT_NO_EMPTY);
         $tags = [];
         foreach ($parts as $part) {
@@ -744,7 +744,7 @@ class Controller extends \yii\base\Controller
      */
     protected function parseDocCommentDetail($reflection)
     {
-        $comment = strtr(trim(preg_replace('/^\s*\**( |\t)?/m', '', trim($reflection->getDocComment(), '/'))), "\r", '');
+        $comment = strtr(trim(preg_replace('/^\s*\**([ \t])?/m', '', trim($reflection->getDocComment(), '/'))), "\r", '');
         if (preg_match('/^\s*@\w+/m', $comment, $matches, PREG_OFFSET_CAPTURE)) {
             $comment = trim(substr($comment, 0, $matches[0][1]));
         }
diff --git a/framework/console/controllers/AssetController.php b/framework/console/controllers/AssetController.php
index cd9c3aeaff..5215066df4 100644
--- a/framework/console/controllers/AssetController.php
+++ b/framework/console/controllers/AssetController.php
@@ -677,7 +677,7 @@ EOD;
             return str_replace($inputUrl, $outputUrl, $fullMatch);
         };
 
-        $cssContent = preg_replace_callback('/url\(["\']?([^)^"^\']*)["\']?\)/i', $callback, $cssContent);
+        $cssContent = preg_replace_callback('/url\(["\']?([^)^"\']*)["\']?\)/i', $callback, $cssContent);
 
         return $cssContent;
     }
diff --git a/framework/db/ActiveRecord.php b/framework/db/ActiveRecord.php
index 0b95da9e62..130285617e 100644
--- a/framework/db/ActiveRecord.php
+++ b/framework/db/ActiveRecord.php
@@ -214,7 +214,7 @@ class ActiveRecord extends BaseActiveRecord
         $aliases = array_diff(array_keys($tables), $tables);
 
         return array_map(function ($alias) {
-            return preg_replace('/{{([\w]+)}}/', '$1', $alias);
+            return preg_replace('/{{(\w+)}}/', '$1', $alias);
         }, array_values($aliases));
     }
 
diff --git a/framework/db/sqlite/Command.php b/framework/db/sqlite/Command.php
index 36b2b73124..8bf4c16ec0 100644
--- a/framework/db/sqlite/Command.php
+++ b/framework/db/sqlite/Command.php
@@ -101,7 +101,7 @@ class Command extends \yii\db\Command
      */
     private function extractUsedParams(SqlToken $statement, $params)
     {
-        preg_match_all('/(?P<placeholder>[:][a-zA-Z0-9_]+)/', $statement->getSql(), $matches, PREG_SET_ORDER);
+        preg_match_all('/(?P<placeholder>:\w+)/', $statement->getSql(), $matches, PREG_SET_ORDER);
         $result = [];
         foreach ($matches as $match) {
             $phName = ltrim($match['placeholder'], ':');
diff --git a/framework/helpers/BaseStringHelper.php b/framework/helpers/BaseStringHelper.php
index ba0975fa7e..da13416310 100644
--- a/framework/helpers/BaseStringHelper.php
+++ b/framework/helpers/BaseStringHelper.php
@@ -476,7 +476,7 @@ class BaseStringHelper
             return $string;
         }
 
-        $parts = preg_split('/(\s+[^\w]+\s+|^[^\w]+\s+|\s+)/u', $string, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
+        $parts = preg_split('/(\s+\W+\s+|^\W+\s+|\s+)/u', $string, -1, PREG_SPLIT_NO_EMPTY | PREG_SPLIT_DELIM_CAPTURE);
         $ucfirstEven = trim(mb_substr($parts[0], -1, 1, $encoding)) === '';
         foreach ($parts as $key => $value) {
             $isEven = (bool)($key % 2);
diff --git a/framework/validators/IpValidator.php b/framework/validators/IpValidator.php
index 3bab5f5c3d..c4a9555bf8 100644
--- a/framework/validators/IpValidator.php
+++ b/framework/validators/IpValidator.php
@@ -115,11 +115,11 @@ class IpValidator extends Validator
     /**
      * @var string Regexp-pattern to validate IPv4 address
      */
-    public $ipv4Pattern = '/^(?:(?:2(?:[0-4][0-9]|5[0-5])|[0-1]?[0-9]?[0-9])\.){3}(?:(?:2([0-4][0-9]|5[0-5])|[0-1]?[0-9]?[0-9]))$/';
+    public $ipv4Pattern = '/^(?:(?:2(?:[0-4]\d|5[0-5])|[0-1]?\d?\d)\.){3}(?:(?:2([0-4]\d|5[0-5])|[0-1]?\d?\d))$/';
     /**
      * @var string Regexp-pattern to validate IPv6 address
      */
-    public $ipv6Pattern = '/^(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))$/';
+    public $ipv6Pattern = '/^(([\da-fA-F]{1,4}:){7}[\da-fA-F]{1,4}|([\da-fA-F]{1,4}:){1,7}:|([\da-fA-F]{1,4}:){1,6}:[\da-fA-F]{1,4}|([\da-fA-F]{1,4}:){1,5}(:[\da-fA-F]{1,4}){1,2}|([\da-fA-F]{1,4}:){1,4}(:[\da-fA-F]{1,4}){1,3}|([\da-fA-F]{1,4}:){1,3}(:[\da-fA-F]{1,4}){1,4}|([\da-fA-F]{1,4}:){1,2}(:[\da-fA-F]{1,4}){1,5}|[\da-fA-F]{1,4}:((:[\da-fA-F]{1,4}){1,6})|:((:[\da-fA-F]{1,4}){1,7}|:)|fe80:(:[\da-fA-F]{0,4}){0,4}%[\da-zA-Z]+|::(ffff(:0{1,4})?:)?((25[0-5]|(2[0-4]|1?\d)?\d)\.){3}(25[0-5]|(2[0-4]|1?\d)?\d)|([\da-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1?[\d])?\d)\.){3}(25[0-5]|(2[0-4]|1?\d)?\d))$/';
     /**
      * @var string user-defined error message is used when validation fails due to the wrong IP address format.
      *
diff --git a/framework/web/Request.php b/framework/web/Request.php
index 2c0d4eaccc..d3a716c97f 100644
--- a/framework/web/Request.php
+++ b/framework/web/Request.php
@@ -1198,7 +1198,7 @@ class Request extends \yii\base\Request
     {
         $ip = $this->getSecureForwardedHeaderTrustedPart('for');
         if ($ip !== null && preg_match(
-            '/^\[?(?P<ip>(?:(?:(?:[0-9a-f]{1,4}:){1,6}(?:[0-9a-f]{1,4})?(?:(?::[0-9a-f]{1,4}){1,6}))|(?:[\d]{1,3}\.){3}[\d]{1,3}))\]?(?::(?P<port>[\d]+))?$/',
+            '/^\[?(?P<ip>(?:(?:(?:[0-9a-f]{1,4}:){1,6}(?:[0-9a-f]{1,4})?(?:(?::[0-9a-f]{1,4}){1,6}))|(?:\d{1,3}\.){3}\d{1,3}))\]?(?::(?P<port>\d+))?$/',
             $ip,
             $matches
         )) {
diff --git a/framework/web/Response.php b/framework/web/Response.php
index 8603b4ad90..bc06a4b04d 100644
--- a/framework/web/Response.php
+++ b/framework/web/Response.php
@@ -897,7 +897,7 @@ class Response extends \yii\base\Response
         if ($checkAjax && $request->getIsAjax()) {
             if (
                 in_array($statusCode, [301, 302])
-                && preg_match('/Trident\/|MSIE[ ]/', (string)$request->userAgent)
+                && preg_match('/Trident\/|MSIE /', (string)$request->userAgent)
             ) {
                 $statusCode = 200;
             }