diff --git a/core/lib/utils/string_convert.dart b/core/lib/utils/string_convert.dart
index d105a6233..ac95df361 100644
--- a/core/lib/utils/string_convert.dart
+++ b/core/lib/utils/string_convert.dart
@@ -181,7 +181,7 @@ class StringConvert {
         input = Uri.decodeComponent(input);
       }
 
-      if (input.length % 4 == 0 && _base64ValidationRegex.hasMatch(input)) {
+      if (input.length % 4 == 0 && !input.contains(' ') && _base64ValidationRegex.hasMatch(input)) {
         try {
           input = utf8.decode(base64.decode(input));
         } catch (_) {}
diff --git a/core/test/utils/redos_vulnerability_test.dart b/core/test/utils/redos_vulnerability_test.dart
index 1ef1f1755..672e7a3a9 100644
--- a/core/test/utils/redos_vulnerability_test.dart
+++ b/core/test/utils/redos_vulnerability_test.dart
@@ -474,7 +474,7 @@ void main() {
 
       test('Should handle emails with special characters - valid cases', () {
         // Valid emails that should be extracted successfully
-        final validEmailInputs = {
+        final validEmailInputs = <String, String>{
           'user+tag@example.com': 'user+tag@example.com',
           'user.name@example.com': 'user.name@example.com',
           'user_name@example.com': 'user_name@example.com',
@@ -487,12 +487,12 @@ void main() {
           'user@例え.jp': 'user@例え.jp',
           '${'a' * 64}@example.com': '${'a' * 64}@example.com',
           'Contact us at support@example.com for help': 'support@example.com',
-          'Multiple emails: alice@test.com, bob@test.org': contains('alice@test.com'),
+          'Multiple emails: alice@test.com, bob@test.org': 'alice@test.com',
         };
 
         for (final entry in validEmailInputs.entries) {
           final input = entry.key;
-          final expectedMatch = entry.value;
+          final expectedEmail = entry.value;
 
           final stopwatch = Stopwatch()..start();
           final result = StringConvert.extractEmailAddress(input);
@@ -501,13 +501,8 @@ void main() {
           expect(stopwatch.elapsedMilliseconds, lessThan(100),
               reason: 'Should process quickly: $input');
 
-          if (expectedMatch is String) {
-            expect(result, contains(expectedMatch),
-                reason: 'Should extract "$expectedMatch" from: $input');
-          } else {
-            expect(result, expectedMatch,
-                reason: 'Should match expected pattern from: $input');
-          }
+          expect(result, contains(expectedEmail),
+              reason: 'Should extract "$expectedEmail" from: $input');
         }
       });
 
@@ -658,8 +653,8 @@ void main() {
             StringConvert.extractEmailAddress(input);
             StringConvert.isTextTable('$input\n$input');
             HtmlUtils.extractPlainText(input);
-          } catch (e) {
-            // It's OK if these fail, we're just testing performance
+          } catch (_) {
+            // Intentionally ignored - focus is on performance, not correctness
           }
 
           stopwatch.stop();