From 7299ff9326636d8dd04c6a5226d9cae8a6faf994 Mon Sep 17 00:00:00 2001
From: Brian Clozel <brian.clozel@broadcom.com>
Date: Mon, 23 Feb 2026 11:02:22 +0100
Subject: [PATCH] Improve ResourceHttpMessageConverter target type support

This commit updates the target type detection in
`ResourceHttpMessageConverter` to only support target types that are
relevant: `InputStreamResource` for streaming, and types assignable from
`ByteArrayResource` for non-streaming cases.

Closes gh-36368
---
 .../ResourceHttpMessageConverter.java         |  2 +-
 .../ResourceHttpMessageConverterTests.java    | 44 ++++++++++++++++++-
 2 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/spring-web/src/main/java/org/springframework/http/converter/ResourceHttpMessageConverter.java b/spring-web/src/main/java/org/springframework/http/converter/ResourceHttpMessageConverter.java
index e4ce4097520..6ffb2f7d72a 100644
--- a/spring-web/src/main/java/org/springframework/http/converter/ResourceHttpMessageConverter.java
+++ b/spring-web/src/main/java/org/springframework/http/converter/ResourceHttpMessageConverter.java
@@ -93,7 +93,7 @@ public class ResourceHttpMessageConverter extends AbstractHttpMessageConverter<R
 				}
 			};
 		}
-		else if (Resource.class == clazz || ByteArrayResource.class.isAssignableFrom(clazz)) {
+		else if (clazz.isAssignableFrom(ByteArrayResource.class)) {
 			byte[] body = StreamUtils.copyToByteArray(inputMessage.getBody());
 			return new ByteArrayResource(body) {
 				@Override
diff --git a/spring-web/src/test/java/org/springframework/http/converter/ResourceHttpMessageConverterTests.java b/spring-web/src/test/java/org/springframework/http/converter/ResourceHttpMessageConverterTests.java
index be2377c8b70..db890399a3f 100644
--- a/spring-web/src/test/java/org/springframework/http/converter/ResourceHttpMessageConverterTests.java
+++ b/spring-web/src/test/java/org/springframework/http/converter/ResourceHttpMessageConverterTests.java
@@ -26,6 +26,7 @@ import org.junit.jupiter.api.Test;
 import org.springframework.core.io.ByteArrayResource;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.InputStreamResource;
+import org.springframework.core.io.InputStreamSource;
 import org.springframework.core.io.Resource;
 import org.springframework.http.ContentDisposition;
 import org.springframework.http.MediaType;
@@ -41,6 +42,7 @@ import static org.mockito.BDDMockito.willThrow;
 import static org.mockito.Mockito.mock;
 
 /**
+ * Tests for {@link ResourceHttpMessageConverter}.
  * @author Arjen Poutsma
  * @author Kazuki Shimizu
  * @author Brian Clozel
@@ -52,13 +54,15 @@ class ResourceHttpMessageConverterTests {
 
 	@Test
 	void canReadResource() {
-		assertThat(converter.canRead(Resource.class, new MediaType("application", "octet-stream"))).isTrue();
+		assertThat(converter.canRead(Resource.class, MediaType.APPLICATION_OCTET_STREAM)).isTrue();
+		assertThat(converter.canRead(ByteArrayResource.class, MediaType.APPLICATION_OCTET_STREAM)).isTrue();
 	}
 
 	@Test
 	void canWriteResource() {
-		assertThat(converter.canWrite(Resource.class, new MediaType("application", "octet-stream"))).isTrue();
+		assertThat(converter.canWrite(Resource.class, MediaType.APPLICATION_OCTET_STREAM)).isTrue();
 		assertThat(converter.canWrite(Resource.class, MediaType.ALL)).isTrue();
+		assertThat(converter.canWrite(ByteArrayResource.class, MediaType.ALL)).isTrue();
 	}
 
 	@Test
@@ -73,6 +77,17 @@ class ResourceHttpMessageConverterTests {
 		assertThat(actualResource.getFilename()).isEqualTo("yourlogo.jpg");
 	}
 
+	@Test // gh-36368
+	void shouldNotReadAsUnknownType() throws IOException {
+		byte[] body = FileCopyUtils.copyToByteArray(getClass().getResourceAsStream("logo.jpg"));
+		MockHttpInputMessage inputMessage = new MockHttpInputMessage(body);
+		inputMessage.getHeaders().setContentType(MediaType.IMAGE_JPEG);
+		inputMessage.getHeaders().setContentDisposition(
+				ContentDisposition.attachment().filename("yourlogo.jpg").build());
+		assertThatExceptionOfType(HttpMessageNotReadableException.class).isThrownBy(() ->
+				converter.read(CustomResource.class, inputMessage));
+	}
+
 	@Test  // SPR-13443
 	public void shouldReadInputStreamResource() throws IOException {
 		try (InputStream body = getClass().getResourceAsStream("logo.jpg") ) {
@@ -100,6 +115,16 @@ class ResourceHttpMessageConverterTests {
 		}
 	}
 
+	@Test // gh-36368
+	public void shouldNotReadStreamResourceAsUnknownType() throws IOException {
+		try (InputStream body = getClass().getResourceAsStream("logo.jpg") ) {
+			MockHttpInputMessage inputMessage = new MockHttpInputMessage(body);
+			inputMessage.getHeaders().setContentType(MediaType.IMAGE_JPEG);
+			assertThatExceptionOfType(HttpMessageNotReadableException.class).isThrownBy(() ->
+					converter.read(CustomStreamResource.class, inputMessage));
+		}
+	}
+
 	@Test
 	void shouldWriteImageResource() throws IOException {
 		MockHttpOutputMessage outputMessage = new MockHttpOutputMessage();
@@ -157,4 +182,19 @@ class ResourceHttpMessageConverterTests {
 		assertThat(outputMessage.getHeaders().getContentLength()).isEqualTo(0);
 	}
 
+	static class CustomStreamResource extends InputStreamResource {
+
+		public CustomStreamResource(InputStreamSource inputStreamSource) {
+			super(inputStreamSource);
+		}
+
+	}
+
+	static class CustomResource extends ByteArrayResource {
+
+		public CustomResource(byte[] byteArray) {
+			super(byteArray);
+		}
+	}
+
 }