xss_clean() improvement

Fixes this: https://github.com/EllisLab/CodeIgniter/issues/2667#issuecomment-37819186

2 files changed, 10 insertions, 4 deletions

diff --git a/system/core/Security.php b/system/core/Security.php
index faa52d746..1dfea18f8 100644
--- a/system/core/Security.php
+++ b/system/core/Security.php
@@ -578,13 +578,13 @@ class CI_Security {
 
 		do
 		{
-			$m1 = $m2 = 0;
+			$str_compare = $str;
 
-			$str = preg_replace('/(&#x0*[0-9a-f]{2,5})(?![0-9a-f;])/iS', '$1;', $str, -1, $m1);
-			$str = preg_replace('/(&#\d{2,4})(?![0-9;])/S', '$1;', $str, -1, $m2);
+			$str = preg_replace('/(&#x0*[0-9a-f]{2,5})(?![0-9a-f;])/iS', '$1;', $str);
+			$str = preg_replace('/(&#\d{2,4})(?![0-9;])/S', '$1;', $str);
 			$str = html_entity_decode($str, ENT_COMPAT, $charset);
 		}
-		while ($m1 OR $m2);
+		while ($str_compare !== $str);
 
 		return $str;
 	}
diff --git a/tests/codeigniter/core/Security_test.php b/tests/codeigniter/core/Security_test.php
index 433ad313f..14e042ee2 100644
--- a/tests/codeigniter/core/Security_test.php
+++ b/tests/codeigniter/core/Security_test.php
@@ -71,6 +71,12 @@ class Security_test extends CI_TestCase {
 		$this->assertEquals("Hello, i try to [removed]alert('Hack');[removed] your site", $harmless_string);
 	}
 
+	public function test_xss_clean_entity_double_encoded()
+	{
+		$input = '<a href="&#38&#35&#49&#48&#54&#38&#35&#57&#55&#38&#35&#49&#49&#56&#38&#35&#57&#55&#38&#35&#49&#49&#53&#38&#35&#57&#57&#38&#35&#49&#49&#52&#38&#35&#49&#48&#53&#38&#35&#49&#49&#50&#38&#35&#49&#49&#54&#38&#35&#53&#56&#38&#35&#57&#57&#38&#35&#49&#49&#49&#38&#35&#49&#49&#48&#38&#35&#49&#48&#50&#38&#35&#49&#48&#53&#38&#35&#49&#49&#52&#38&#35&#49&#48&#57&#38&#35&#52&#48&#38&#35&#52&#57&#38&#35&#52&#49">Clickhere</a>';
+		$this->assertEquals('<a 1>Clickhere</a>', $this->security->xss_clean($input));
+	}
+
 	// --------------------------------------------------------------------
 
 	public function test_xss_hash()