diff --git a/src/js/_enqueues/admin/media-frame-upload.js b/src/js/_enqueues/admin/media-frame-upload.js
index f5af17d7991d2..464818e51e697 100644
--- a/src/js/_enqueues/admin/media-frame-upload.js
+++ b/src/js/_enqueues/admin/media-frame-upload.js
@@ -202,16 +202,12 @@
 
 				/*
 				 * Early mime type scanning for images, as wp-plupload.js does,
-				 * extended with the formats the client-side pipeline accepts.
+				 * for the formats the pipeline processes.
 				 */
-				const image = /(?:jpe?g|png|gif|webp|avif|heic|heif)$/i.exec(
-					file.name
-				);
-				if ( image ) {
+				const subtype = pipeline.getImageSubtype( file.name );
+				if ( subtype ) {
 					attributes.type = 'image';
-					// `jpg` is not a valid subtype, so map it to `jpeg`.
-					const subtype = image[ 0 ].toLowerCase();
-					attributes.subtype = 'jpg' === subtype ? 'jpeg' : subtype;
+					attributes.subtype = subtype;
 				}
 
 				const model = wp.media.model.Attachment.create( attributes );
diff --git a/src/js/_enqueues/admin/media-upload-pipeline.js b/src/js/_enqueues/admin/media-upload-pipeline.js
index 58dceae7affcc..bd25774d48491 100644
--- a/src/js/_enqueues/admin/media-upload-pipeline.js
+++ b/src/js/_enqueues/admin/media-upload-pipeline.js
@@ -38,6 +38,13 @@ window.wp = window.wp || {};
 
 	const imageSizeCount = Object.keys( settings.allImageSizes || {} ).length;
 
+	/*
+	 * Image subtypes the pipeline processes. Keep in sync with
+	 * CLIENT_SIDE_SUPPORTED_MIME_TYPES and HEIC_MIME_TYPES in the
+	 * upload-media package.
+	 */
+	const IMAGE_SUBTYPES = [ 'jpeg', 'png', 'gif', 'webp', 'avif', 'heic', 'heif' ];
+
 	/**
 	 * Recursively appends data to a FormData object, supporting nested objects.
 	 *
@@ -412,16 +419,73 @@ window.wp = window.wp || {};
 		return configured && isStoreConfigured();
 	}
 
+	/**
+	 * Gets the image subtype of a file name the pipeline can process.
+	 *
+	 * @param {string} fileName A file name.
+	 * @return {string|null} The subtype, eg. `jpeg` for `photo.jpg`, or
+	 *                       null when the pipeline does not process it.
+	 */
+	function getImageSubtype( fileName ) {
+		const match = /\.([a-z0-9]+)$/i.exec( fileName || '' );
+		if ( ! match ) {
+			return null;
+		}
+		// `jpg` is not a valid subtype, so map it to `jpeg`.
+		const extension = match[ 1 ].toLowerCase();
+		const subtype = 'jpg' === extension ? 'jpeg' : extension;
+		return IMAGE_SUBTYPES.includes( subtype ) ? subtype : null;
+	}
+
+	/**
+	 * Whether a file is an image the client-side pipeline can process.
+	 *
+	 * A file whose type is missing from the allowed types the page was
+	 * rendered with is left to the server, which can allow it for a single
+	 * request (see partitionBatch()). A HEIC file is also matched by its
+	 * extension, since browsers on platforms without a HEIC codec may give
+	 * it no type at all.
+	 *
+	 * @param {plupload.File} file A file added to the plupload queue.
+	 * @return {boolean} True when the pipeline should take the file.
+	 */
+	function isPipelineFile( file ) {
+		const type = ( file.type || '' ).toLowerCase();
+		const allowedTypes = settings.allowedMimeTypes;
+		if (
+			type &&
+			allowedTypes &&
+			! Object.values( allowedTypes ).includes( type )
+		) {
+			return false;
+		}
+		if (
+			type.startsWith( 'image/' ) &&
+			IMAGE_SUBTYPES.includes( type.slice( 6 ) )
+		) {
+			return true;
+		}
+		const subtype = getImageSubtype( file.name );
+		return 'heic' === subtype || 'heif' === subtype;
+	}
+
 	/**
 	 * Splits a batch of plupload files between the pipeline and classic
 	 * plupload.
 	 *
-	 * Audio files stay classic so they keep the title and description that
-	 * media_handle_upload() derives from their ID3 tags, which the REST
-	 * endpoint does not do. So do JPEG and PNG images while plupload's own
-	 * client-side resize is enabled (the "Scale images" setting, or a
-	 * `resize` passed through `plupload_init`): plupload scales those down
-	 * before uploading them, the pipeline would not.
+	 * Only images the pipeline can process are taken (see isPipelineFile()).
+	 * Everything else, such as audio, video, PDF, SVG or JSON, stays
+	 * classic: the pipeline would do nothing for it but upload it, and
+	 * would check its type against the allowed types the page was rendered
+	 * with instead of the uploader's own filters, which a plugin can extend
+	 * for a single frame. For the same reason an image of a type the page
+	 * was not rendered with stays classic, so the server decides. Audio
+	 * also keeps the title and description that media_handle_upload()
+	 * derives from its ID3 tags, which the REST endpoint does not. JPEG
+	 * and PNG images stay classic too while plupload's own client-side
+	 * resize is enabled (the "Scale images" setting, or a `resize` passed
+	 * through `plupload_init`): plupload scales those down before
+	 * uploading them, the pipeline would not.
 	 *
 	 * The whole batch stays classic when a file cannot be re-queued on
 	 * plupload or is already plupload's: plupload returns no native File
@@ -450,7 +514,7 @@ window.wp = window.wp || {};
 			}
 			const type = file.type || '';
 			if (
-				/^audio\//i.test( type ) ||
+				! isPipelineFile( file ) ||
 				( isResizing && /^image\/(?:jpeg|png)$/i.test( type ) )
 			) {
 				batch.classic.push( file );
@@ -735,5 +799,6 @@ window.wp = window.wp || {};
 		isReady: isReady,
 		routeBatch: routeBatch,
 		getErrorText: getErrorText,
+		getImageSubtype: getImageSubtype,
 	};
 } )( window.wp );
diff --git a/tests/e2e/specs/media-library-client-side-upload.test.js b/tests/e2e/specs/media-library-client-side-upload.test.js
index 0b2dd0ad5e3ac..91773312577c1 100644
--- a/tests/e2e/specs/media-library-client-side-upload.test.js
+++ b/tests/e2e/specs/media-library-client-side-upload.test.js
@@ -9,6 +9,7 @@ import { test, expect } from '@wordpress/e2e-test-utils-playwright';
 import {
 	TEST_IMAGE_PATH,
 	TEST_AUDIO_PATH,
+	TEST_SVG_PATH,
 	SIMULATED_ERROR,
 	UNDECODABLE_HEIC,
 	failMediaCreate,
@@ -565,6 +566,96 @@ test.describe( 'Media Library grid client-side uploads', () => {
 		expect( restUploadCount ).toBe( 0 );
 	} );
 
+	test( 'leaves files that are not processable images to the classic uploader', async ( {
+		page,
+		admin,
+	} ) => {
+		// A plugin can allow an extra type on its own uploader, as page
+		// builders do for SVG, without adding it to the allowed mime types
+		// the page was rendered with.
+		await overridePluploadDefaults( page, {
+			filters: { mime_types: [ { extensions: 'svg' } ] },
+		} );
+		await stubClassicUpload( page );
+		await admin.visitAdminPage( 'upload.php', 'mode=grid' );
+
+		const isolated = await page.evaluate( () =>
+			Boolean( window.crossOriginIsolated )
+		);
+		test.skip(
+			! isolated,
+			'The client-side pipeline requires a cross-origin isolated context'
+		);
+
+		const counts = countUploadRequests( page );
+
+		const fileInput = page.locator( FILE_INPUT_SELECTOR ).first();
+		await expect( fileInput ).toBeAttached( { timeout: 30_000 } );
+		await fileInput.setInputFiles( TEST_SVG_PATH );
+
+		// The uploader's own filter decides, so the file reaches the server
+		// instead of being rejected in the browser.
+		await expect
+			.poll( () => counts.asyncUpload, { timeout: 60_000 } )
+			.toBeGreaterThanOrEqual( 1 );
+		expect( counts.rest ).toBe( 0 );
+		await expect(
+			page.locator( '.upload-error-message', {
+				hasText: 'not allowed to upload this file type',
+			} )
+		).toHaveCount( 0 );
+	} );
+
+	test( 'leaves images of a type the page was not rendered with to the classic uploader', async ( {
+		page,
+		admin,
+	} ) => {
+		// A plugin can allow an image type only for its own requests, so
+		// the allowed mime types the page was rendered with leave it out
+		// while the uploader's own filter lets it through.
+		await page.addInitScript( () => {
+			let settings;
+			Object.defineProperty( window, '_wpMediaUploadPipelineSettings', {
+				configurable: true,
+				get() {
+					return settings;
+				},
+				set( value ) {
+					settings = value;
+					const allowed = value && value.allowedMimeTypes;
+					for ( const extension in allowed || {} ) {
+						if ( 'image/jpeg' === allowed[ extension ] ) {
+							delete allowed[ extension ];
+						}
+					}
+				},
+			} );
+		} );
+		await admin.visitAdminPage( 'upload.php', 'mode=grid' );
+
+		const isolated = await page.evaluate( () =>
+			Boolean( window.crossOriginIsolated )
+		);
+		test.skip(
+			! isolated,
+			'The client-side pipeline requires a cross-origin isolated context'
+		);
+
+		const counts = countUploadRequests( page );
+
+		const fileInput = page.locator( FILE_INPUT_SELECTOR ).first();
+		await expect( fileInput ).toBeAttached( { timeout: 30_000 } );
+		await fileInput.setInputFiles( TEST_IMAGE_PATH );
+
+		// The server decides, as it would without the pipeline.
+		await expect( tile( page, 'test-image' ) ).toBeVisible( {
+			timeout: 60_000,
+		} );
+		expect( counts.asyncUpload ).toBeGreaterThanOrEqual( 1 );
+		expect( counts.rest ).toBe( 0 );
+		await expect( page.locator( '.upload-error' ) ).toHaveCount( 0 );
+	} );
+
 	test( 'splits a batch of an image and audio between the pipeline and the classic uploader', async ( {
 		page,
 		admin,
diff --git a/tests/e2e/utils/media-pipeline.js b/tests/e2e/utils/media-pipeline.js
index c01dc05ebc72d..5db0b7c24779f 100644
--- a/tests/e2e/utils/media-pipeline.js
+++ b/tests/e2e/utils/media-pipeline.js
@@ -18,6 +18,10 @@ export const TEST_AUDIO_PATH = path.join(
 	'../assets/test-audio.wav'
 );
 
+// An SVG: like any file that is not an image the pipeline can process, it
+// stays on the classic upload path.
+export const TEST_SVG_PATH = path.join( __dirname, '../assets/sample.svg' );
+
 // A REST error the pipeline surfaces as-is: its message matches none of the
 // transient patterns @wordpress/upload-media retries on.
 export const SIMULATED_ERROR = {