CVE-2020-13677
📋 TL;DR
CVE-2020-13677 is an access control vulnerability in Drupal's JSON:API module that allows attackers to bypass intended content restrictions. This affects Drupal sites with the JSON:API module enabled, potentially exposing sensitive content to unauthorized users. Sites without this module enabled are not vulnerable.
💻 Affected Systems
- Drupal Core
📦 What is this software?
Drupal by Drupal
Drupal by Drupal
Drupal by Drupal
⚠️ Risk & Real-World Impact
Worst Case
Attackers could access sensitive content like user data, unpublished content, or administrative information that should be restricted, leading to data breaches or privilege escalation.
Likely Case
Unauthorized access to content that should be protected by Drupal's access control system, potentially exposing confidential information.
If Mitigated
With proper network segmentation and access controls, impact is limited to the specific Drupal instance, but exposed data remains vulnerable.
🎯 Exploit Status
Exploitation requires understanding of Drupal's JSON:API endpoints and access control mechanisms, but tools and scripts exist.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Drupal 8.8.11, 8.9.9, 9.0.9 or later
Vendor Advisory: https://www.drupal.org/sa-core-2021-010
Restart Required: No
Instructions:
1. Update Drupal core to the patched version. 2. If using Composer: composer update drupal/core-recommended. 3. If manually updating: download and replace core files. 4. Run update.php or drush updatedb. 5. Clear all caches.
🔧 Temporary Workarounds
Disable JSON:API Module
allTemporarily disable the vulnerable JSON:API module if immediate patching isn't possible
drush pm:uninstall jsonapi
Or disable via Drupal admin interface at /admin/modules
🧯 If You Can't Patch
- Disable the JSON:API module immediately
- Implement web application firewall rules to block suspicious JSON:API requests
🔍 How to Verify
Check if Vulnerable:
Check if JSON:API module is enabled and Drupal version is in affected range: drush status | grep 'Drupal version'Check Version:
drush status | grep 'Drupal version' or check /admin/reports/status in Drupal adminVerify Fix Applied:
Verify Drupal version is 8.8.11+, 8.9.9+, or 9.0.9+ and test JSON:API endpoints with restricted content📡 Detection & Monitoring
Log Indicators:
- Unusual access patterns to JSON:API endpoints
- Requests to /jsonapi/* endpoints returning data that should be restricted
- Increased 200 OK responses on protected content endpoints
Network Indicators:
- Unusual traffic to /jsonapi/* paths
- Requests with specific parameters attempting to bypass filters
SIEM Query:
source="drupal_access.log" AND uri="/jsonapi/*" AND status=200 | stats count by client_ip, uri