diff --git a/CHANGELOG.txt b/CHANGELOG.txt
index 6a20156af04..5ebbf2117cc 100644
--- a/CHANGELOG.txt
+++ b/CHANGELOG.txt
@@ -1,4 +1,8 @@
 
+Drupal 7.56, 2017-06-21
+-----------------------
+- Fixed security issues (access bypass). See SA-CORE-2017-003.
+
 Drupal 7.55, 2017-06-07
 -----------------------
 - Fixed incompatibility with PHP versions 7.0.19 and 7.1.5 due to duplicate
diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index cc0291e81b7..dc4ecf0289d 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -8,7 +8,7 @@
 /**
  * The current system version.
  */
-define('VERSION', '7.55');
+define('VERSION', '7.56');
 
 /**
  * Core API compatibility.
diff --git a/includes/file.inc b/includes/file.inc
index fafc33da53a..fa7f5eb547f 100644
--- a/includes/file.inc
+++ b/includes/file.inc
@@ -1614,6 +1614,20 @@ function file_save_upload($form_field_name, $validators = array(), $destination
 
   // If we made it this far it's safe to record this file in the database.
   if ($file = file_save($file)) {
+    // Track non-public files in the session if they were uploaded by an
+    // anonymous user. This allows modules such as the File module to only
+    // grant view access to the specific anonymous user who uploaded the file.
+    // See file_file_download().
+    // The 'file_public_schema' variable is used to allow other publicly
+    // accessible file schemes to be treated the same as the public:// scheme
+    // provided by Drupal core and to avoid adding unnecessary data to the
+    // session (and the resulting bypass of the page cache) in those cases. For
+    // security reasons, only schemes that are completely publicly accessible,
+    // with no download restrictions, should be added to this variable. See
+    // file_managed_file_value().
+    if (!$user->uid && !in_array($destination_scheme, variable_get('file_public_schema', array('public')))) {
+      $_SESSION['anonymous_allowed_file_ids'][$file->fid] = $file->fid;
+    }
     // Add file to the cache.
     $upload_cache[$form_field_name] = $file;
     return $file;
diff --git a/modules/file/file.module b/modules/file/file.module
index c8e17f85834..fb5e9b949d4 100644
--- a/modules/file/file.module
+++ b/modules/file/file.module
@@ -146,8 +146,9 @@ function file_file_download($uri, $field_type = 'file') {
   // headers for files controlled by other modules. Make an exception for
   // temporary files where the host entity has not yet been saved (for example,
   // an image preview on a node/add form) in which case, allow download by the
-  // file's owner.
-  if (empty($references) && ($file->status == FILE_STATUS_PERMANENT || $file->uid != $user->uid)) {
+  // file's owner. For anonymous file owners, only the browser session that
+  // uploaded the file should be granted access.
+  if (empty($references) && ($file->status == FILE_STATUS_PERMANENT || $file->uid != $user->uid || (!$user->uid && empty($_SESSION['anonymous_allowed_file_ids'][$file->fid])))) {
       return;
   }
 
diff --git a/modules/file/tests/file.test b/modules/file/tests/file.test
index 41e97cdfa34..b3a1424dc5c 100644
--- a/modules/file/tests/file.test
+++ b/modules/file/tests/file.test
@@ -1551,6 +1551,80 @@ class FilePrivateTestCase extends FileFieldTestCase {
     $this->assertNoRaw($node_file->filename, 'File without view field access permission does not appear after attempting to attach it to a new node.');
     $this->drupalGet(file_create_url($node_file->uri));
     $this->assertResponse(403, 'Confirmed that access is denied for the file without view field access permission after attempting to attach it to a new node.');
+
+    // As an anonymous user, create a temporary file with no references and
+    // confirm that only the session that uploaded it may view it.
+    $this->drupalLogout();
+    user_role_grant_permissions(DRUPAL_ANONYMOUS_RID, array(
+      "create $type_name content",
+      'access content',
+    ));
+    $test_file = $this->getTestFile('text');
+    $this->drupalGet('node/add/' . $type_name);
+    $edit = array('files[' . $field_name . '_' . LANGUAGE_NONE . '_0]' => drupal_realpath($test_file->uri));
+    $this->drupalPost(NULL, $edit, t('Upload'));
+    $files = file_load_multiple(array(), array('uid' => 0));
+    $this->assertEqual(1, count($files), 'Loaded one anonymous file.');
+    $file = end($files);
+    $this->assertNotEqual($file->status, FILE_STATUS_PERMANENT, 'File is temporary.');
+    $usage = file_usage_list($file);
+    $this->assertFalse($usage, 'No file usage found.');
+    $file_url = file_create_url($file->uri);
+    $this->drupalGet($file_url);
+    $this->assertResponse(200, 'Confirmed that the anonymous uploader has access to the temporary file.');
+    // Close the prior connection and remove the session cookie.
+    $this->curlClose();
+    $this->cookies = array();
+    $this->drupalGet($file_url);
+    $this->assertResponse(403, 'Confirmed that another anonymous user cannot access the temporary file.');
+
+    // As an anonymous user, create a permanent file that is referenced by a
+    // published node and confirm that all anonymous users may view it.
+    $test_file = $this->getTestFile('text');
+    $this->drupalGet('node/add/' . $type_name);
+    $edit = array();
+    $edit['title'] = $this->randomName();
+    $edit['files[' . $field_name . '_' . LANGUAGE_NONE . '_0]'] = drupal_realpath($test_file->uri);
+    $this->drupalPost(NULL, $edit, t('Save'));
+    $new_node = $this->drupalGetNodeByTitle($edit['title']);
+    $file = file_load($new_node->{$field_name}[LANGUAGE_NONE][0]['fid']);
+    $this->assertEqual($file->status, FILE_STATUS_PERMANENT, 'File is permanent.');
+    $usage = file_usage_list($file);
+    $this->assertTrue($usage, 'File usage found.');
+    $file_url = file_create_url($file->uri);
+    $this->drupalGet($file_url);
+    $this->assertResponse(200, 'Confirmed that the anonymous uploader has access to the permanent file that is referenced by a published node.');
+    // Close the prior connection and remove the session cookie.
+    $this->curlClose();
+    $this->cookies = array();
+    $this->drupalGet($file_url);
+    $this->assertResponse(200, 'Confirmed that another anonymous user also has access to the permanent file that is referenced by a published node.');
+
+    // As an anonymous user, create a permanent file that is referenced by an
+    // unpublished node and confirm that no anonymous users may view it (even
+    // the session that uploaded the file) because they cannot view the
+    // unpublished node.
+    $test_file = $this->getTestFile('text');
+    $this->drupalGet('node/add/' . $type_name);
+    $edit = array();
+    $edit['title'] = $this->randomName();
+    $edit['files[' . $field_name . '_' . LANGUAGE_NONE . '_0]'] = drupal_realpath($test_file->uri);
+    $this->drupalPost(NULL, $edit, t('Save'));
+    $new_node = $this->drupalGetNodeByTitle($edit['title']);
+    $new_node->status = NODE_NOT_PUBLISHED;
+    node_save($new_node);
+    $file = file_load($new_node->{$field_name}[LANGUAGE_NONE][0]['fid']);
+    $this->assertEqual($file->status, FILE_STATUS_PERMANENT, 'File is permanent.');
+    $usage = file_usage_list($file);
+    $this->assertTrue($usage, 'File usage found.');
+    $file_url = file_create_url($file->uri);
+    $this->drupalGet($file_url);
+    $this->assertResponse(403, 'Confirmed that the anonymous uploader cannot access the permanent file when it is referenced by an unpublished node.');
+    // Close the prior connection and remove the session cookie.
+    $this->curlClose();
+    $this->cookies = array();
+    $this->drupalGet($file_url);
+    $this->assertResponse(403, 'Confirmed that another anonymous user cannot access the permanent file when it is referenced by an unpublished node.');
   }
 }