diff --git a/.github/workflows/_meta-build.yaml b/.github/workflows/_meta-build.yaml
index 6c2651b6ce..534556becd 100644
--- a/.github/workflows/_meta-build.yaml
+++ b/.github/workflows/_meta-build.yaml
@@ -34,7 +34,7 @@ jobs:
         uses: actions/setup-java@99b8673ff64fbf99d8d325f52d9a5bdedb8483e9 # tag=v4.2.1
         with:
           distribution: 'temurin'
-          java-version: '17'
+          java-version: '21'
           cache: 'maven'
 
       - name: Setup CycloneDX CLI
diff --git a/.github/workflows/ci-release.yaml b/.github/workflows/ci-release.yaml
index fb12df5410..d340410adf 100644
--- a/.github/workflows/ci-release.yaml
+++ b/.github/workflows/ci-release.yaml
@@ -57,7 +57,7 @@ jobs:
         uses: actions/setup-java@99b8673ff64fbf99d8d325f52d9a5bdedb8483e9 # tag=v4.2.1
         with:
           distribution: 'temurin'
-          java-version: '17'
+          java-version: '21'
           cache: 'maven'
 
       - name: Set Version
diff --git a/.github/workflows/ci-test.yaml b/.github/workflows/ci-test.yaml
index 8b1793ef63..b5a4281479 100644
--- a/.github/workflows/ci-test.yaml
+++ b/.github/workflows/ci-test.yaml
@@ -39,7 +39,7 @@ jobs:
         uses: actions/setup-java@99b8673ff64fbf99d8d325f52d9a5bdedb8483e9 # tag=v4.2.1
         with:
           distribution: 'temurin'
-          java-version: '17'
+          java-version: '21'
           cache: 'maven'
 
       - name: Execute unit tests
diff --git a/DEVELOPING.md b/DEVELOPING.md
index 03bfb0460a..63584c7d40 100644
--- a/DEVELOPING.md
+++ b/DEVELOPING.md
@@ -18,7 +18,7 @@ This document primarily covers the API server. Please refer to the frontend repo
 
 There are a few things you'll need on your journey:
 
-* JDK 17+ ([Temurin](https://adoptium.net/temurin/releases) distribution recommended)
+* JDK 21+ ([Temurin](https://adoptium.net/temurin/releases) distribution recommended)
 * Maven (comes bundled with IntelliJ and Eclipse)
 * A Java IDE of your preference (we recommend IntelliJ, but any other IDE is fine as well)
 * Docker (optional)
diff --git a/pom.xml b/pom.xml
index 05f08fddd5..3707d434ee 100644
--- a/pom.xml
+++ b/pom.xml
@@ -80,6 +80,10 @@
     </ciManagement>
 
     <properties>
+        <!-- Java Version -->
+        <maven.compiler.source>21</maven.compiler.source>
+        <maven.compiler.target>21</maven.compiler.target>
+
         <!-- Dependency Versions -->
         <frontend.version>4.11.0</frontend.version>
         <lib.alpine.version>${project.parent.version}</lib.alpine.version>
diff --git a/src/main/java/org/dependencytrack/tasks/NistApiMirrorTask.java b/src/main/java/org/dependencytrack/tasks/NistApiMirrorTask.java
index d82ac2ae8e..ebea83b0c3 100644
--- a/src/main/java/org/dependencytrack/tasks/NistApiMirrorTask.java
+++ b/src/main/java/org/dependencytrack/tasks/NistApiMirrorTask.java
@@ -146,13 +146,12 @@ public void inform(final Event e) {
                 .namingPattern(getClass().getSimpleName() + "-%d")
                 .uncaughtExceptionHandler(new LoggableUncaughtExceptionHandler())
                 .build();
-        final var executor = new ThreadPoolExecutor(1, 1, 0L, TimeUnit.SECONDS, new LinkedBlockingQueue<>(), factory);
 
         final long startTimeNs = System.nanoTime();
         final var numMirrored = new AtomicInteger(0);
         ZonedDateTime lastModified;
         try (final NvdCveClient client = createApiClient(apiUrl, apiKey, lastModifiedEpochSeconds)) {
-            try {
+            try (final var executor = new ThreadPoolExecutor(1, 1, 0L, TimeUnit.SECONDS, new LinkedBlockingQueue<>(), factory)) {
                 while (client.hasNext()) {
                     for (final DefCveItem defCveItem : client.next()) {
                         final CveItem cveItem = defCveItem.getCve();
@@ -186,28 +185,6 @@ public void inform(final Event e) {
                         });
                     }
                 }
-            } finally {
-                // Copied from ExecutorService#close (available since JDK 19).
-                // This code can be replaced with try-with-resources after upgrade to Java 21.
-                // https://github.com/openjdk/jdk/blob/890adb6410dab4606a4f26a942aed02fb2f55387/src/java.base/share/classes/java/util/concurrent/ExecutorService.java#L410-L429
-                boolean terminated = executor.isTerminated();
-                if (!terminated) {
-                    executor.shutdown();
-                    boolean interrupted = false;
-                    while (!terminated) {
-                        try {
-                            terminated = executor.awaitTermination(1L, TimeUnit.DAYS);
-                        } catch (InterruptedException ex) {
-                            if (!interrupted) {
-                                executor.shutdownNow();
-                                interrupted = true;
-                            }
-                        }
-                    }
-                    if (interrupted) {
-                        Thread.currentThread().interrupt();
-                    }
-                }
             }
 
             lastModified = client.getLastUpdated();