diff --git src/wp-admin/includes/image.php src/wp-admin/includes/image.php
index d8d5d5b34b..ec24d77c00 100644
--- src/wp-admin/includes/image.php
+++ src/wp-admin/includes/image.php
@@ -647,18 +647,27 @@ function wp_generate_attachment_metadata( $attachment_id, $file ) {
  * @since 2.5.0
  *
  * @param string $str
- * @return int|float
+ * @return int|float Returns 0 on failure.
  */
 function wp_exif_frac2dec( $str ) {
-	if ( false === strpos( $str, '/' ) ) {
-		return $str;
+	// Fractions must contain a single `/`.
+	if ( false === strpos( $str, '/' ) || substr_count( $str, '/' ) > 1 ) {
+		return 0;
 	}
 
 	list( $numerator, $denominator ) = explode( '/', $str );
-	if ( ! empty( $denominator ) ) {
-		return $numerator / $denominator;
+
+	// Both the numerator and the denominator must be numbers.
+	if ( ! is_numeric( $numerator ) || ! is_numeric( $denominator ) ) {
+		return 0;
+	}
+
+	// The denominator must not be empty (or 0).
+	if ( empty( $denominator ) ) {
+		return 0;
 	}
-	return $str;
+
+	return $numerator / $denominator;
 }
 
 /**
diff --git tests/phpunit/tests/image/functions.php tests/phpunit/tests/image/functions.php
index 488731a0e8..5ce882d9c9 100644
--- tests/phpunit/tests/image/functions.php
+++ tests/phpunit/tests/image/functions.php
@@ -700,4 +700,94 @@ class Tests_Image_Functions extends WP_UnitTestCase {
 			unlink( $temp_dir . $size['file'] );
 		}
 	}
+
+	/**
+	 * Test for wp_exif_frac2dec verified that it properly handles edge cases
+	 * and always returns an int or float, 0 for failures.
+	 *
+	 * @ticket 54385
+	 * @dataProvider data_test_wp_exif_frac2dec
+	 */
+	public function test_wp_exif_frac2dec( $fraction, $expect ) {
+		$this->assertSame( $expect, wp_exif_frac2dec( $fraction ) );
+	}
+
+
+	/**
+	 * Data provider for testing `wp_exif_frac2dec()`.
+	 *
+	 * @return array {
+	 *     Arguments for testing `wp_exif_frac2dec()`.
+	 *
+	 *     @type string|null        $fraction       The fraction string to run.
+	 *     @type int|float       $expected    The resulting expected value.
+	 *
+	 */
+	public function data_test_wp_exif_frac2dec() {
+		global $wpdb;
+
+		return array(
+			array(
+				'0/0',
+				0,
+			),
+			array(
+				'0/abc',
+				0,
+			),
+			array(
+				'0.0',
+				0,
+			),
+			array(
+				'010',
+				0,
+			),
+			array(
+				10.123,
+				0,
+			),
+			array(
+				'50/100',
+				0.5,
+			),
+			array(
+				'25/100',
+				.25,
+			),
+			array(
+				'0',
+				0,
+			),
+			array(
+				'100/0',
+				0,
+			),
+			array(
+				'path/to/file',
+				0,
+			),
+			array(
+				'123notafraction',
+				0,
+			),
+			array(
+				'/',
+				0,
+			),
+			array(
+				'1/2/3',
+				0,
+			),
+			array(
+				'///',
+				0,
+			),
+			array(
+				'4/2',
+				2,
+			),
+		);
+	}
+
 }