diff --git a/15_dtls/java-dtls-src/dtls-server/pom.xml b/15_dtls/java-dtls-src/dtls-server/pom.xml
index 563153f..09ffd17 100644
--- a/15_dtls/java-dtls-src/dtls-server/pom.xml
+++ b/15_dtls/java-dtls-src/dtls-server/pom.xml
@@ -20,7 +20,7 @@
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.12</version>
+            <version>4.13.1</version>
             <scope>test</scope>
         </dependency>
         <!-- https://mvnrepository.com/artifact/org.eclipse.californium/scandium -->