diff --git a/apps/dav/lib/CardDAV/ImageExportPlugin.php b/apps/dav/lib/CardDAV/ImageExportPlugin.php
index 31e8ed6a5e5..e48410d26d6 100644
--- a/apps/dav/lib/CardDAV/ImageExportPlugin.php
+++ b/apps/dav/lib/CardDAV/ImageExportPlugin.php
@@ -87,6 +87,7 @@ class ImageExportPlugin extends ServerPlugin {
 
 		if ($result = $this->getPhoto($node)) {
 			$response->setHeader('Content-Type', $result['Content-Type']);
+			$response->setHeader('Content-Disposition', 'attachment');
 			$response->setStatus(200);
 
 			$response->setBody($result['body']);
@@ -121,6 +122,17 @@ class ImageExportPlugin extends ServerPlugin {
 				}
 				$val = file_get_contents($val);
 			}
+
+			$allowedContentTypes = [
+				'image/png',
+				'image/jpeg',
+				'image/gif',
+			];
+
+			if(!in_array($type, $allowedContentTypes, true)) {
+				$type = 'application/octet-stream';
+			}
+
 			return [
 				'Content-Type' => $type,
 				'body' => $val
diff --git a/apps/dav/tests/unit/CardDAV/ImageExportPluginTest.php b/apps/dav/tests/unit/CardDAV/ImageExportPluginTest.php
index 229fa7ec6f2..e878cbd4f59 100644
--- a/apps/dav/tests/unit/CardDAV/ImageExportPluginTest.php
+++ b/apps/dav/tests/unit/CardDAV/ImageExportPluginTest.php
@@ -107,9 +107,20 @@ class ImageExportPluginTest extends TestCase {
 		$this->plugin->expects($this->once())->method('getPhoto')->willReturn($getPhotoResult);
 
 		if (!$expected) {
-			$this->response->expects($this->once())->method('setHeader');
-			$this->response->expects($this->once())->method('setStatus');
-			$this->response->expects($this->once())->method('setBody');
+			$this->response
+				->expects($this->at(0))
+				->method('setHeader')
+				->with('Content-Type', $getPhotoResult['Content-Type']);
+			$this->response
+				->expects($this->at(1))
+				->method('setHeader')
+				->with('Content-Disposition', 'attachment');
+			$this->response
+				->expects($this->once())
+				->method('setStatus');
+			$this->response
+				->expects($this->once())
+				->method('setBody');
 		}
 
 		$result = $this->plugin->httpGet($this->request, $this->response);
@@ -142,12 +153,43 @@ class ImageExportPluginTest extends TestCase {
 
 	public function providesPhotoData() {
 		return [
-			'empty vcard' => [false, ''],
-			'vcard without PHOTO' => [false, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nEND:VCARD\r\n"],
-			'vcard 3 with PHOTO' => [['Content-Type' => 'image/jpeg', 'body' => '12345'], "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nPHOTO;ENCODING=b;TYPE=JPEG:MTIzNDU=\r\nEND:VCARD\r\n"],
-			'vcard 3 with PHOTO URL' => [false, "BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nPHOTO;TYPE=JPEG;VALUE=URI:http://example.com/photo.jpg\r\nEND:VCARD\r\n"],
-			'vcard 4 with PHOTO' => [['Content-Type' => 'image/jpeg', 'body' => '12345'], "BEGIN:VCARD\r\nVERSION:4.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nPHOTO:data:image/jpeg;base64,MTIzNDU=\r\nEND:VCARD\r\n"],
-			'vcard 4 with PHOTO URL' => [false, "BEGIN:VCARD\r\nVERSION:4.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nPHOTO;MEDIATYPE=image/jpeg:http://example.org/photo.jpg\r\nEND:VCARD\r\n"],
+			'empty vcard' => [
+				false,
+				''
+			],
+			'vcard without PHOTO' => [
+				false,
+				"BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nEND:VCARD\r\n"
+			],
+			'vcard 3 with PHOTO' => [
+				[
+					'Content-Type' => 'image/jpeg',
+					'body' => '12345'
+				],
+				"BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nPHOTO;ENCODING=b;TYPE=JPEG:MTIzNDU=\r\nEND:VCARD\r\n"
+			],
+			'vcard 3 with PHOTO URL' => [
+				false,
+				"BEGIN:VCARD\r\nVERSION:3.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nPHOTO;TYPE=JPEG;VALUE=URI:http://example.com/photo.jpg\r\nEND:VCARD\r\n"
+			],
+			'vcard 4 with PHOTO' => [
+				[
+					'Content-Type' => 'image/jpeg',
+					'body' => '12345'
+				],
+				"BEGIN:VCARD\r\nVERSION:4.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nPHOTO:data:image/jpeg;base64,MTIzNDU=\r\nEND:VCARD\r\n"
+			],
+			'vcard 4 with PHOTO URL' => [
+				false,
+				"BEGIN:VCARD\r\nVERSION:4.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nPHOTO;MEDIATYPE=image/jpeg:http://example.org/photo.jpg\r\nEND:VCARD\r\n"
+			],
+			'vcard 4 with PHOTO AND INVALID MIMEtYPE' => [
+				[
+					'Content-Type' => 'application/octet-stream',
+					'body' => '12345'
+				],
+				"BEGIN:VCARD\r\nVERSION:4.0\r\nPRODID:-//Sabre//Sabre VObject 3.5.0//EN\r\nUID:12345\r\nFN:12345\r\nN:12345;;;;\r\nPHOTO:data:image/svg;base64,MTIzNDU=\r\nEND:VCARD\r\n"
+			],
 		];
 	}
 }