diff --git a/system/libraries/Session/Session_driver.php b/system/libraries/Session/Session_driver.php
index bef5ee4..2fe30b8 100644
--- a/system/libraries/Session/Session_driver.php
+++ b/system/libraries/Session/Session_driver.php
@@ -113,6 +113,23 @@
 	// ------------------------------------------------------------------------
 
 	/**
+	 * PHP 5.x validate ID
+	 *
+	 * Enforces session.use_strict_mode on PHP 5.x (7+ does it by itself)
+	 *
+	 * @return	void
+	 */
+	public function php5_validate_id()
+	{
+		if (PHP_VERSION_ID < 70000 && isset($_COOKIE[$this->_config['cookie_name']]) && ! $this->validateId($_COOKIE[$this->_config['cookie_name']]))
+		{
+			unset($_COOKIE[$this->_config['cookie_name']]);
+		}
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
 	 * Cookie destroy
 	 *
 	 * Internal method to force removal of a cookie by the client
diff --git a/system/libraries/Session/drivers/Session_database_driver.php b/system/libraries/Session/drivers/Session_database_driver.php
index ae7a1b4..074accf 100644
--- a/system/libraries/Session/drivers/Session_database_driver.php
+++ b/system/libraries/Session/drivers/Session_database_driver.php
@@ -133,6 +133,8 @@
 			return $this->_fail();
 		}
 
+		$this->php5_validate_id();
+
 		return $this->_success;
 	}
 
@@ -340,6 +342,30 @@
 			: $this->_fail();
 	}
 
+	// --------------------------------------------------------------------
+
+	/**
+	 * Validate ID
+	 *
+	 * Checks whether a session ID record exists server-side,
+	 * to enforce session.use_strict_mode.
+	 *
+	 * @param	string	$id
+	 * @return	bool
+	 */
+	public function validateId($id)
+	{
+		// Prevent previous QB calls from messing with our queries
+		$this->_db->reset_query();
+
+		$this->_db->select('1')->from($this->_config['save_path'])->where('id', $id);
+		empty($this->_config['match_ip']) OR $this->_db->where('ip_address', $_SERVER['REMOTE_ADDR']);
+		$result = $this->_db->get();
+		empty($result) OR $result = $result->row();
+
+		return ! empty($result);
+	}
+
 	// ------------------------------------------------------------------------
 
 	/**
diff --git a/system/libraries/Session/drivers/Session_files_driver.php b/system/libraries/Session/drivers/Session_files_driver.php
index c6d789a..654f300 100644
--- a/system/libraries/Session/drivers/Session_files_driver.php
+++ b/system/libraries/Session/drivers/Session_files_driver.php
@@ -148,6 +148,8 @@
 			.$name // we'll use the session cookie name as a prefix to avoid collisions
 			.($this->_config['match_ip'] ? md5($_SERVER['REMOTE_ADDR']) : '');
 
+		$this->php5_validate_id();
+
 		return $this->_success;
 	}
 
@@ -392,6 +394,22 @@
 	// --------------------------------------------------------------------
 
 	/**
+	 * Validate ID
+	 *
+	 * Checks whether a session ID record exists server-side,
+	 * to enforce session.use_strict_mode.
+	 *
+	 * @param	string	$id
+	 * @return	bool
+	 */
+	public function validateId($id)
+	{
+		return is_file($this->_file_path.$id);
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
 	 * Byte-safe strlen()
 	 *
 	 * @param	string	$str
diff --git a/system/libraries/Session/drivers/Session_memcached_driver.php b/system/libraries/Session/drivers/Session_memcached_driver.php
index b109738..7d8e390 100644
--- a/system/libraries/Session/drivers/Session_memcached_driver.php
+++ b/system/libraries/Session/drivers/Session_memcached_driver.php
@@ -145,6 +145,8 @@
 			return $this->_fail();
 		}
 
+		$this->php5_validate_id();
+
 		return $this->_success;
 	}
 
@@ -290,6 +292,23 @@
 		return $this->_success;
 	}
 
+	// --------------------------------------------------------------------
+
+	/**
+	 * Validate ID
+	 *
+	 * Checks whether a session ID record exists server-side,
+	 * to enforce session.use_strict_mode.
+	 *
+	 * @param	string	$id
+	 * @return	bool
+	 */
+	public function validateId($id)
+	{
+		$this->_memcached-get($this->_key_prefix.$id);
+		return ($this->_memcached->getResultCode() === Memcached::RES_SUCCESS);
+	}
+
 	// ------------------------------------------------------------------------
 
 	/**
diff --git a/system/libraries/Session/drivers/Session_redis_driver.php b/system/libraries/Session/drivers/Session_redis_driver.php
index 413c30d..d7a5755 100644
--- a/system/libraries/Session/drivers/Session_redis_driver.php
+++ b/system/libraries/Session/drivers/Session_redis_driver.php
@@ -153,6 +153,8 @@
 			return $this->_success;
 		}
 
+		$this->php5_validate_id();
+
 		return $this->_fail();
 	}
 
@@ -310,6 +312,22 @@
 		return $this->_success;
 	}
 
+	// --------------------------------------------------------------------
+
+	/**
+	 * Validate ID
+	 *
+	 * Checks whether a session ID record exists server-side,
+	 * to enforce session.use_strict_mode.
+	 *
+	 * @param	string	$id
+	 * @return	bool
+	 */
+	public function validateId($id)
+	{
+		return (bool) $this->_redis->exists($this->_key_prefix.$id);
+	}
+
 	// ------------------------------------------------------------------------
 
 	/**