diff --git a/src/Orchard.Core.Tests/Common/BbcodeFilterTests.cs b/src/Orchard.Core.Tests/Common/BbcodeFilterTests.cs
index 0172995b1..984ac276d 100644
--- a/src/Orchard.Core.Tests/Common/BbcodeFilterTests.cs
+++ b/src/Orchard.Core.Tests/Common/BbcodeFilterTests.cs
@@ -34,5 +34,28 @@ namespace Orchard.Core.Tests.Common {
             var processed = _filter.ProcessContent(text, null);
             Assert.That(processed, Is.EqualTo("foo <a href=\"alink\">bar</a> baz"));
         }
+
+        [Test]
+        public void ShouldIgnoreMalformedUrl() {
+            const string text = "foo [url]bar baz";
+            var processed = _filter.ProcessContent(text, null);
+            Assert.That(processed, Is.EqualTo("foo [url]bar baz"));
+        }
+
+        [Test]
+        public void ShouldIgnoreMalformedUrlWithTitle() {
+            const string text = "foo [url=alink]bar baz";
+            var processed = _filter.ProcessContent(text, null);
+            Assert.That(processed, Is.EqualTo("foo [url=alink]bar baz"));
+        }
+
+        [Test]
+        public void ShouldIgnoreMalformedImg() {
+            const string text = "foo [img]bar baz";
+            var processed = _filter.ProcessContent(text, null);
+            Assert.That(processed, Is.EqualTo("foo [img]bar baz"));
+        }
+
+
     }
 }
\ No newline at end of file
diff --git a/src/Orchard.Web/Core/Common/Services/BbcodeFilter.cs b/src/Orchard.Web/Core/Common/Services/BbcodeFilter.cs
index 4ec096980..a6c7aea40 100644
--- a/src/Orchard.Web/Core/Common/Services/BbcodeFilter.cs
+++ b/src/Orchard.Web/Core/Common/Services/BbcodeFilter.cs
@@ -32,6 +32,11 @@ namespace Orchard.Core.Common.Services {
 
             foreach(var start in allIndexes) {
                 var end = text.IndexOf("[/url]", start, StringComparison.Ordinal);
+                
+                if (end == -1) {
+                    continue;
+                }
+                
                 var url = text.Substring(start + 5 , end - start - 5);
 
                 // substitue [url] by <a>
@@ -50,6 +55,11 @@ namespace Orchard.Core.Common.Services {
             foreach (var start in allIndexes) {
                 var urlEnd = text.IndexOf("]", start, StringComparison.Ordinal);
                 var end = text.IndexOf("[/url]", start, StringComparison.Ordinal);
+                
+                if (end == -1) {
+                    continue;
+                }
+                
                 var url = text.Substring(start + 5, urlEnd - start - 5);
                 var title = text.Substring(urlEnd + 1, end - urlEnd - 1);
 
@@ -68,6 +78,11 @@ namespace Orchard.Core.Common.Services {
 
             foreach (var start in allIndexes) {
                 var end = text.IndexOf("[/img]", start, StringComparison.Ordinal);
+                
+                if (end == -1) {
+                    continue;
+                }
+                
                 var url = text.Substring(start + 5, end - start - 5);
 
                 // substitue [url] by <a>