diff --git a/common/pom.xml b/common/pom.xml
index 5392bfe4..1cb156e6 100644
--- a/common/pom.xml
+++ b/common/pom.xml
@@ -127,6 +127,18 @@
             <artifactId>junit-jupiter</artifactId>
         </dependency>
 
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>${version.org.mockito.mockito-junit-jupiter}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-junit-jupiter</artifactId>
+            <scope>test</scope>
+        </dependency>
+
         <dependency>
             <groupId>io.github.resilience4j</groupId>
             <artifactId>resilience4j-retry</artifactId>
diff --git a/common/src/main/java/org/fiware/tmforum/common/repository/TmForumRepository.java b/common/src/main/java/org/fiware/tmforum/common/repository/TmForumRepository.java
index 7bc29a81..620c062e 100644
--- a/common/src/main/java/org/fiware/tmforum/common/repository/TmForumRepository.java
+++ b/common/src/main/java/org/fiware/tmforum/common/repository/TmForumRepository.java
@@ -104,9 +104,9 @@ public <T> Mono<PagedResult<T>> findEntities(Integer offset, Integer limit, Stri
      * {@code typeToClass} instead of a single fixed class.
      */
     public <T> Mono<PagedResult<T>> findEntitiesPolymorphic(Integer offset, Integer limit, String types,
-                                          String query, String orderBy, Function<String, Class<? extends T>> typeToClass) {
+                                          String query, String ids, String orderBy, Function<String, Class<? extends T>> typeToClass) {
         return entitiesApi.queryEntities(generalProperties.getTenant(),
-                        null,
+                        ids,
                         null,
                         types,
                         null,
diff --git a/common/src/main/java/org/fiware/tmforum/common/rest/AbstractApiController.java b/common/src/main/java/org/fiware/tmforum/common/rest/AbstractApiController.java
index 9497c5a9..853320ee 100644
--- a/common/src/main/java/org/fiware/tmforum/common/rest/AbstractApiController.java
+++ b/common/src/main/java/org/fiware/tmforum/common/rest/AbstractApiController.java
@@ -182,6 +182,7 @@ protected <R> Mono<Stream<R>> listPolymorphic(Integer offset, Integer limit, Str
 				.findEntitiesPolymorphic(offset, limit,
 						Optional.ofNullable(queryParams).map(QueryParams::type).orElse(types),
 						Optional.ofNullable(queryParams).map(QueryParams::query).orElse(null),
+						Optional.ofNullable(queryParams).map(QueryParams::id).orElse(null),
 						orderBy,
 						typeToClass)
 				.doOnNext(pagedResult -> optionalHttpRequest.ifPresent(theRequest -> {
diff --git a/common/src/test/java/org/fiware/tmforum/common/repository/TmForumRepositoryTest.java b/common/src/test/java/org/fiware/tmforum/common/repository/TmForumRepositoryTest.java
index 69042c42..07a22431 100644
--- a/common/src/test/java/org/fiware/tmforum/common/repository/TmForumRepositoryTest.java
+++ b/common/src/test/java/org/fiware/tmforum/common/repository/TmForumRepositoryTest.java
@@ -1,12 +1,20 @@
 package org.fiware.tmforum.common.repository;
 
 import io.micronaut.http.HttpResponse;
+import org.fiware.ngsi.api.EntitiesApiClient;
+import org.fiware.ngsi.model.EntityListVO;
 import org.fiware.tmforum.common.configuration.GeneralProperties;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import reactor.core.publisher.Mono;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
 
 class TmForumRepositoryTest {
 
@@ -19,6 +27,28 @@ public void setUp() {
 		repository = new TmForumRepository(properties, null, null, null, null, null);
 	}
 
+	@Test
+	public void findEntitiesPolymorphicForwardsTheIdFilterToTheBroker() {
+		// Regression test: findEntitiesPolymorphic used to hard-code the broker's native
+		// "id" query param to null, silently dropping any ?id= filter on polymorphic list
+		// endpoints (e.g. resourceSpecification, which spans several NGSI-LD types).
+		EntitiesApiClient entitiesApi = mock(EntitiesApiClient.class);
+		TmForumRepository repositoryWithClient = new TmForumRepository(properties, entitiesApi, null, null, null, null);
+		String requestedId = "urn:ngsi-ld:software-specification:0e2d5c4a-cf51-43cf-a510-dff06f62f4a3";
+
+		when(entitiesApi.queryEntities(any(), any(), any(), any(), any(), any(), any(), any(), any(), any(), any(),
+				any(), any(), any(), any(), any(), any()))
+				.thenReturn(Mono.just(HttpResponse.ok(new EntityListVO())));
+
+		repositoryWithClient
+				.findEntitiesPolymorphic(0, 10, "software-specification,resource-specification", null, requestedId,
+						null, type -> Object.class)
+				.block();
+
+		verify(entitiesApi).queryEntities(eq(properties.getTenant()), eq(requestedId), any(), any(), any(), any(),
+				any(), any(), any(), any(), any(), any(), any(), any(), any(), any(), any());
+	}
+
 	@Test
 	public void extractsTheConfiguredHeader() {
 		properties.setCountHeader("NGSILD-Results-Count");
diff --git a/common/src/test/java/org/fiware/tmforum/common/rest/AbstractApiControllerTest.java b/common/src/test/java/org/fiware/tmforum/common/rest/AbstractApiControllerTest.java
new file mode 100644
index 00000000..94c21a4a
--- /dev/null
+++ b/common/src/test/java/org/fiware/tmforum/common/rest/AbstractApiControllerTest.java
@@ -0,0 +1,58 @@
+package org.fiware.tmforum.common.rest;
+
+import io.micronaut.http.HttpRequest;
+import io.micronaut.http.context.ServerRequestContext;
+import org.fiware.tmforum.common.configuration.GeneralProperties;
+import org.fiware.tmforum.common.querying.MyPojo;
+import org.fiware.tmforum.common.querying.QueryParser;
+import org.fiware.tmforum.common.repository.PagedResult;
+import org.fiware.tmforum.common.repository.TmForumRepository;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+import reactor.core.publisher.Mono;
+
+import java.util.List;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+class AbstractApiControllerTest {
+
+	private static class TestController extends AbstractApiController<MyPojo> {
+		TestController(QueryParser queryParser, TmForumRepository repository) {
+			super(queryParser, null, repository, null);
+		}
+	}
+
+	@AfterEach
+	public void clearRequestContext() {
+		ServerRequestContext.set(null);
+	}
+
+	@Test
+	public void listPolymorphicForwardsTheIdFilterToTheRepository() {
+		// Regression test: listPolymorphic used to only forward "type" and "query" from the
+		// parsed request to the repository, silently dropping any ?id= filter - even though it
+		// was correctly parsed into QueryParams.id(). The non-polymorphic list() already forwarded
+		// it; listPolymorphic must do the same.
+		GeneralProperties properties = new GeneralProperties();
+		QueryParser queryParser = new QueryParser(properties);
+		TmForumRepository repository = mock(TmForumRepository.class);
+		TestController controller = new TestController(queryParser, repository);
+
+		String requestedId = "urn:ngsi-ld:software-specification:0e2d5c4a-cf51-43cf-a510-dff06f62f4a3";
+		ServerRequestContext.set(
+				HttpRequest.GET("/resourceSpecification?id=" + requestedId + "&fields=lifecycleStatus"));
+
+		when(repository.findEntitiesPolymorphic(any(), any(), any(), any(), any(), any(), any()))
+				.thenReturn(Mono.just(new PagedResult<>(List.of(), 0, 10, null)));
+
+		controller.listPolymorphic(0, 10, "software-specification,resource-specification", MyPojo.class,
+				type -> MyPojo.class).block();
+
+		verify(repository).findEntitiesPolymorphic(any(), any(), any(), any(), eq(requestedId), any(), any());
+	}
+}