diff --git a/documentation/src/docs/asciidoc/release-notes/release-notes-5.10.4.adoc b/documentation/src/docs/asciidoc/release-notes/release-notes-5.10.4.adoc
index bb4452fcdd5c..072648f73b47 100644
--- a/documentation/src/docs/asciidoc/release-notes/release-notes-5.10.4.adoc
+++ b/documentation/src/docs/asciidoc/release-notes/release-notes-5.10.4.adoc
@@ -15,7 +15,8 @@ on GitHub.
 
 ==== Bug Fixes
 
-* ❓
+* Fixed potential locking issue with `ExclusiveResource` in the
+  `HierarchicalTestExecutorService`, which could lead to deadlocks in certain scenarios.
 
 ==== Deprecations and Breaking Changes
 
diff --git a/junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/CompositeLock.java b/junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/CompositeLock.java
index 18b628b0fdde..3718d82a64fc 100644
--- a/junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/CompositeLock.java
+++ b/junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/CompositeLock.java
@@ -28,7 +28,7 @@ class CompositeLock implements ResourceLock {
 
 	// for tests only
 	List<Lock> getLocks() {
-		return locks;
+		return this.locks;
 	}
 
 	@Override
@@ -38,9 +38,9 @@ public ResourceLock acquire() throws InterruptedException {
 	}
 
 	private void acquireAllLocks() throws InterruptedException {
-		List<Lock> acquiredLocks = new ArrayList<>(locks.size());
+		List<Lock> acquiredLocks = new ArrayList<>(this.locks.size());
 		try {
-			for (Lock lock : locks) {
+			for (Lock lock : this.locks) {
 				lock.lockInterruptibly();
 				acquiredLocks.add(lock);
 			}
@@ -53,7 +53,7 @@ private void acquireAllLocks() throws InterruptedException {
 
 	@Override
 	public void release() {
-		release(locks);
+		release(this.locks);
 	}
 
 	private void release(List<Lock> acquiredLocks) {
@@ -64,20 +64,20 @@ private void release(List<Lock> acquiredLocks) {
 
 	private class CompositeLockManagedBlocker implements ForkJoinPool.ManagedBlocker {
 
-		private boolean acquired;
+		private volatile boolean acquired;
 
 		@Override
 		public boolean block() throws InterruptedException {
-			if (!acquired) {
+			if (!this.acquired) {
 				acquireAllLocks();
-				acquired = true;
+				this.acquired = true;
 			}
 			return true;
 		}
 
 		@Override
 		public boolean isReleasable() {
-			return acquired;
+			return this.acquired;
 		}
 
 	}
diff --git a/junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/SingleLock.java b/junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/SingleLock.java
index b5f6e80d8089..e568b9a8f5c0 100644
--- a/junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/SingleLock.java
+++ b/junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/SingleLock.java
@@ -26,7 +26,7 @@ class SingleLock implements ResourceLock {
 
 	// for tests only
 	Lock getLock() {
-		return lock;
+		return this.lock;
 	}
 
 	@Override
@@ -37,25 +37,25 @@ public ResourceLock acquire() throws InterruptedException {
 
 	@Override
 	public void release() {
-		lock.unlock();
+		this.lock.unlock();
 	}
 
 	private class SingleLockManagedBlocker implements ForkJoinPool.ManagedBlocker {
 
-		private boolean acquired;
+		private volatile boolean acquired;
 
 		@Override
 		public boolean block() throws InterruptedException {
-			if (!acquired) {
-				lock.lockInterruptibly();
-				acquired = true;
+			if (!this.acquired) {
+				SingleLock.this.lock.lockInterruptibly();
+				this.acquired = true;
 			}
 			return true;
 		}
 
 		@Override
 		public boolean isReleasable() {
-			return acquired || (acquired = lock.tryLock());
+			return this.acquired || (this.acquired = SingleLock.this.lock.tryLock());
 		}
 
 	}