diff --git a/CHANGELOG.md b/CHANGELOG.md
index c74d963..53082e2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,12 @@
 CHANGELOG
 =========
 
+6.7.2
+-----
+
+* Fixed AUD claim validation in `LtiServiceClient`
+* Fixed empty validation key assignment to the security configuration
+
 6.7.1
 -----
 
diff --git a/src/Security/Jwt/Configuration/ConfigurationFactory.php b/src/Security/Jwt/Configuration/ConfigurationFactory.php
index 4f2a0b9..1e936cf 100644
--- a/src/Security/Jwt/Configuration/ConfigurationFactory.php
+++ b/src/Security/Jwt/Configuration/ConfigurationFactory.php
@@ -85,7 +85,9 @@ private function findAlgorithm(?KeyInterface $signingKey = null, ?KeyInterface $
     private function convertKey(?KeyInterface $key = null): Key
     {
         if (null === $key) {
-            return InMemory::plainText('');
+            return method_exists(InMemory::class, 'empty')
+                ? InMemory::empty()
+                : InMemory::plainText('');
         }
 
         return $this->converter->convert($key);
diff --git a/src/Service/Client/LtiServiceClient.php b/src/Service/Client/LtiServiceClient.php
index ec3e3ae..18f07dc 100644
--- a/src/Service/Client/LtiServiceClient.php
+++ b/src/Service/Client/LtiServiceClient.php
@@ -25,6 +25,7 @@
 use GuzzleHttp\Client;
 use GuzzleHttp\ClientInterface;
 use GuzzleHttp\Exception\ClientException;
+use InvalidArgumentException;
 use OAT\Library\Lti1p3Core\Exception\LtiException;
 use OAT\Library\Lti1p3Core\Exception\LtiExceptionInterface;
 use OAT\Library\Lti1p3Core\Message\Payload\MessagePayloadInterface;
@@ -197,6 +198,14 @@ private function generateCredentials(RegistrationInterface $registration): strin
                 throw new LtiException('Tool key chain is not configured');
             }
 
+            if ($registration->getPlatform()->getAudience() === '') {
+                throw new InvalidArgumentException('Platform audience cannot be null');
+            }
+
+            if ($registration->getPlatform()->getOAuth2AccessTokenUrl() === null) {
+                throw new InvalidArgumentException('Platform OAuth2 access token url cannot be null');
+            }
+
             $token = $this->builder->build(
                 [
                     MessagePayloadInterface::HEADER_KID => $toolKeyChain->getIdentifier()
diff --git a/tests/Traits/DomainTestingTrait.php b/tests/Traits/DomainTestingTrait.php
index 8b52cb7..56aab4c 100644
--- a/tests/Traits/DomainTestingTrait.php
+++ b/tests/Traits/DomainTestingTrait.php
@@ -197,6 +197,60 @@ private function createTestRegistrationWithoutToolLaunchUrl(
         );
     }
 
+    private function createTestRegistrationWithoutPlatformAudience(
+        string $identifier = 'registrationIdentifier',
+        string $clientId = 'registrationClientId',
+        string $platformJwksUrl = 'http://platform.com/jwks',
+        string $toolJwksUrl = 'http://tool.com/jwks'
+    ): Registration {
+        $tool = $this->createTestTool();
+
+        return new Registration(
+            $identifier,
+            $clientId,
+            new Platform(
+                'platformIdentifier',
+                'platformName',
+                '',
+                'http://platform.com/oidc-auth',
+                'http://platform.com/access-token'
+            ),
+            $this->createTestTool(),
+            ['deploymentIdentifier'],
+            $this->createTestKeyChain('platformKeyChain'),
+            $this->createTestKeyChain('toolKeyChain'),
+            $platformJwksUrl,
+            $toolJwksUrl
+        );
+    }
+
+    private function createTestRegistrationWithoutPlatformOAuth2AccessTokenUrl(
+        string $identifier = 'registrationIdentifier',
+        string $clientId = 'registrationClientId',
+        string $platformJwksUrl = 'http://platform.com/jwks',
+        string $toolJwksUrl = 'http://tool.com/jwks'
+    ): Registration {
+        $tool = $this->createTestTool();
+
+        return new Registration(
+            $identifier,
+            $clientId,
+            new Platform(
+                'platformIdentifier',
+                'platformName',
+                'platformAudience',
+                'http://platform.com/oidc-auth',
+                null
+            ),
+            $this->createTestTool(),
+            ['deploymentIdentifier'],
+            $this->createTestKeyChain('platformKeyChain'),
+            $this->createTestKeyChain('toolKeyChain'),
+            $platformJwksUrl,
+            $toolJwksUrl
+        );
+    }
+
     private function createTestRegistrationRepository(array $registrations = []): RegistrationRepositoryInterface
     {
         $registrations = !empty($registrations)
diff --git a/tests/Unit/Service/Client/LtiServiceClientTest.php b/tests/Unit/Service/Client/LtiServiceClientTest.php
index 17069da..1759618 100644
--- a/tests/Unit/Service/Client/LtiServiceClientTest.php
+++ b/tests/Unit/Service/Client/LtiServiceClientTest.php
@@ -519,6 +519,26 @@ public function testItThrowAnLtiExceptionOnPlatformEndpointFailureAfterAutoRetry
         $this->subject->request($this->registration, 'GET', 'http://example.com', [], $scopes);
     }
 
+    public function testItThrowsAnLtiExceptionOnNullPlatformAudience(): void
+    {
+        $this->expectException(LtiException::class);
+        $this->expectExceptionMessage('Cannot generate credentials: Platform audience cannot be null');
+
+        $this->registration = $this->createTestRegistrationWithoutPlatformAudience();
+
+        $this->subject->request($this->registration, 'GET', 'http://example.com');
+    }
+
+    public function testItThrowsAnLtiExceptionOnNullPlatformOAuth2AccessTokenUrl(): void
+    {
+        $this->expectException(LtiException::class);
+        $this->expectExceptionMessage('Cannot generate credentials: Platform OAuth2 access token url cannot be null');
+
+        $this->registration = $this->createTestRegistrationWithoutPlatformOAuth2AccessTokenUrl();
+
+        $this->subject->request($this->registration, 'GET', 'http://example.com');
+    }
+
     private function generateAccessTokenCacheKey(RegistrationInterface $registration, array $scopes = []): string
     {
         return sprintf(