Custom REST API Endpoint may expose data unprividedged users.

Summary

An incorrect capability check in the distributor/list-pull-content REST API endpoint may expose private data, content.raw, users without the correct permissions.

Details

The custom REST API endpoint uses the check_read_permission() function to determine if a user can read the content. While this function is correct for checking if a user can read content, the result is used to determine if the user can read data that is intended to be private:

distributor/includes/rest-api.php

Lines 466 to 486 in 753c325

    
           	if ( ! check_read_permission( $post ) ) { 
        
           		continue; 
        
           	} 
        
           	$formatted_posts[] = array( 
        
           		'id'             => $post->ID, 
        
           		'title'          => array( 'rendered' => $post->post_title ), 
        
           		'excerpt'        => array( 'rendered' => $post->post_excerpt ), 
        
           		'content'        => array( 'raw' => $post->post_content ), 
        
           		'password'       => $post->post_password, 
        
           		'date'           => $post->post_date, 
        
           		'date_gmt'       => $post->post_date_gmt, 
        
           		'guid'           => array( 'rendered' => $post->guid ), 
        
           		'modified'       => $post->post_modified, 
        
           		'modified_gmt'   => $post->post_modified_gmt, 
        
           		'type'           => $post->post_type, 
        
           		'link'           => get_the_permalink( $post ), 
        
           		'comment_status' => $post->comment_status, 
        
           		'ping_status'    => $post->ping_status, 
        
           	); 
        
           }

The effected data is:

$post->post_title (should be obtained via get_the_title())
$post->post_excerpt (should be run through the get_the_excerpt filter)
$post->post_content (should be run obtained via Utils\get_processed_content())
$post->post_password (should not be shared)
$post->guid (should be run through the get_the_guid filter)

Users with the edit_post meta capability are permitted to read each of these items in their unmodified (raw) forms.

PoC

Configuration

Set up a Distributor site from scratch (WP + the plugin only)
Add a subscriber user (wpcli command here for ease)
Log in as the subscriber
Create an application password

POC using default "Hello World" Post

Run a curl request in the edit context for the WP Post endpoint curl 'http://subscriber:apppassword@example.local/wp-json/wp/v2/posts/1?context=edit'
Observe result: Sorry, you are not allowed to edit this post.
Run a curl request to the distributor endpoint curl -XPOST 'http://subscriber:apppassword@example.local/wp-json/wp/v2/distributor/list-pull-content'
Observe the result: post contains raw data

Impact

Data exposure

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Custom REST API Endpoint may expose data unprividedged users.

Package

Affected versions

Patched versions

Description

Summary

Details

PoC

Impact

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	if ( ! check_read_permission( $post ) ) {
	continue;
	}

	$formatted_posts[] = array(
	'id' => $post->ID,
	'title' => array( 'rendered' => $post->post_title ),
	'excerpt' => array( 'rendered' => $post->post_excerpt ),
	'content' => array( 'raw' => $post->post_content ),
	'password' => $post->post_password,
	'date' => $post->post_date,
	'date_gmt' => $post->post_date_gmt,
	'guid' => array( 'rendered' => $post->guid ),
	'modified' => $post->post_modified,
	'modified_gmt' => $post->post_modified_gmt,
	'type' => $post->post_type,
	'link' => get_the_permalink( $post ),
	'comment_status' => $post->comment_status,
	'ping_status' => $post->ping_status,
	);
	}