diff --git a/projects/plugins/jetpack/changelog/fix-too-large-detected-image-size b/projects/plugins/jetpack/changelog/fix-too-large-detected-image-size
new file mode 100644
index 0000000000000..0868b862bfdc6
--- /dev/null
+++ b/projects/plugins/jetpack/changelog/fix-too-large-detected-image-size
@@ -0,0 +1,4 @@
+Significance: patch
+Type: other
+
+Jetpack Sync: Avoid detecting invalid image size
diff --git a/projects/plugins/jetpack/class.jetpack-post-images.php b/projects/plugins/jetpack/class.jetpack-post-images.php
index b41f919869149..995272ddc84b2 100644
--- a/projects/plugins/jetpack/class.jetpack-post-images.php
+++ b/projects/plugins/jetpack/class.jetpack-post-images.php
@@ -519,7 +519,7 @@ public static function from_html( $html_or_id, $width = 200, $height = 200 ) {
 			$width  = (int) $image_tag->getAttribute( 'width' );
 			$height = (int) $image_tag->getAttribute( 'height' );
 			if ( 0 === $width && 0 === $height ) {
-				preg_match( '/-([0-9]+)x([0-9]+)\.(?:jpg|jpeg|png|gif|webp)$/i', $img_src, $matches );
+				preg_match( '/-([0-9]{1,5})x([0-9]{1,5})\.(?:jpg|jpeg|png|gif|webp)$/i', $img_src, $matches );
 				if ( ! empty( $matches[1] ) ) {
 					$width = (int) $matches[1];
 				}
diff --git a/projects/plugins/jetpack/tests/php/media/test-class.jetpack-post-images.php b/projects/plugins/jetpack/tests/php/media/test-class.jetpack-post-images.php
index 02c6fad97a3ba..01267265ffdf5 100644
--- a/projects/plugins/jetpack/tests/php/media/test-class.jetpack-post-images.php
+++ b/projects/plugins/jetpack/tests/php/media/test-class.jetpack-post-images.php
@@ -40,6 +40,35 @@ public function test_from_html_double_quotes() {
 		$this->assertEquals( 200, $result[0]['src_height'] );
 	}
 
+	/**
+	 * Test image size extract in src filename
+	 *
+	 * @covers Jetpack_PostImages::from_html
+	 */
+	public function test_from_html_size() {
+		$s = "<img src='img-2300x1300.jpg' />";
+
+		$result = Jetpack_PostImages::from_html( $s );
+
+		$this->assertIsArray( $result );
+		$this->assertNotEmpty( $result );
+		$this->assertEquals( 2300, $result[0]['src_width'] );
+		$this->assertEquals( 1300, $result[0]['src_height'] );
+	}
+
+	/**
+	 * Test ignoring unrealistic image sizes from src filename
+	 *
+	 * @covers Jetpack_PostImages::from_html
+	 */
+	public function test_from_html_no_size() {
+		$s = "<img src='img-851958915511220x220.jpg' />";
+
+		$result = Jetpack_PostImages::from_html( $s );
+
+		$this->assertEquals( array(), $result );
+	}
+
 	/**
 	 * @author scotchfield
 	 * @covers Jetpack_PostImages::from_slideshow