Fix Information Disclosure vulnerability in the HTML style sanitizer

reported by somerandomdev

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 - Fix Cross-Site-Scripting vulnerability via SVG's animate tag
+- Fix Information Disclosure vulnerability in the HTML style sanitizer
 
 ## Release 1.5.11
 

program/lib/Roundcube/rcube_utils.php

@@ -565,6 +565,9 @@ class rcube_utils
                                 $value .= ' url(' . $url . ')';
                             }
                         }
+                    } elseif (preg_match('/;.*/', $val)) {
+                        // Invalid or evil content, ignore
+                        continue;
                     } else {
                         // whitelist ?
                         $value .= ' ' . $val;

tests/Framework/Utils.php

@@ -291,9 +291,9 @@ class Framework_Utils extends PHPUnit\Framework\TestCase
         $mod = rcube_utils::mod_css_styles($style, 'rcmbody', true);
         $this->assertSame("#rcmbody { content: ''; color: red; }", $mod);
 
-        $style = "body { content: '< page: ;/style>< page: ;img src onerror=\"alert(\'hello\');\">'; color: red; }";
+        $style = "body { content: '< page: ;/style>< page: ;img src onerror=\"alert(\\'hello\\');\">'; color: red; }";
         $mod = rcube_utils::mod_css_styles($style, 'rcmbody', true);
-        $this->assertSame("#rcmbody { content: '< page: ;/style>< page: ;img src onerror=\"alert('hello');\">'; color: red; }", $mod);
+        $this->assertSame("#rcmbody { color: red; }", $mod);
 
         // Removing page: property
         $style = "body { page: test; color: red }";

tests/Framework/Washtml.php

@@ -291,6 +291,13 @@ class Framework_Washtml extends PHPUnit\Framework\TestCase
         $washed = $washer->wash($html);
 
         $this->assertTrue(strpos($washed, $exp) !== false, "Style quotes XSS issue (#1490227)");
+
+        $html = '<div style=\'content: "\0026quot;; background: url(//http.cat/418); content:""; width: 100%; height: 100%;\'>test</div>';
+
+        $washer = new \rcube_washtml();
+        $washed = $washer->wash($html);
+
+        $this->assertTrue(strpos($washed, '<div x-washed="style">test</div>') !== false);
     }
 
     /**