diff --git a/web/undertow/simple/pom.xml b/web/undertow/simple/pom.xml
index 541194a..5f2c4e6 100644
--- a/web/undertow/simple/pom.xml
+++ b/web/undertow/simple/pom.xml
@@ -20,7 +20,7 @@
         <dependency>
             <groupId>io.undertow</groupId>
             <artifactId>undertow-core</artifactId>
-            <version>2.3.20.Final</version>
+            <version>2.3.21.Final</version>
         </dependency>
 
     </dependencies>