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The CVE-2026-8491 vulnerability resides in the Drupal Node View Permissions module. This module is designed to restrict access to node viewing based on user roles and permissions. The flaw is an improper check for unusual or exceptional conditions, leading to a forceful browsing attack. In practice, the module fails to validate certain edge cases where a node’s view permission is overridden or inherited from non‑standard contexts (e.g., unpublished nodes, node references inside paragraphs, or Ajax callbacks). An unauthenticated or low‑privileged attacker can craft direct HTTP requests to node URLs that should be inaccessible, bypassing the intended permission logic. The root cause is that the module does not consistently re‑evaluate access when unusual request patterns occur, such as missing referrer headers, malformed query parameters, or concurrent session states. Specifically, the hook `node_access()` implementation does not account for exceptional conditions like nodes being temporarily locked, under revision preview, or accessed via entity API wrappers without proper context. Attackers can exploit this by enumerating node IDs (nid) and sending GET requests with manipulated `_format` or `_wrapper_format` parameters, causing the module to skip its custom access checks and fall back to Drupal core’s default `node_access` logic, which may grant view access. Versions affected are all releases before 1.7.0 (for the 1.x branch) and before 2.0.1 (for the 2.x branch). The module’s access handler does not properly handle `NULL` user objects or anonymous sessions with partial authentication tokens, leading to inconsistent `$op == ‘view’` decisions. A successful forceful browse reveals node s, bodies, fields, and attached media that should be restricted to specific roles (e.g., editors or content managers). The vulnerability is rated Medium because it requires the attacker to guess or brute‑force node IDs, and the target site must have the Node View Permissions module installed with custom view restrictions. Drupal.org released fixed versions 1.7.0 and 2.0.1 on May 12, 2026, patching the missing exceptional condition checks by adding rigorous input validation and access re‑evaluation on every node load.
dailycve form:
Platform: Drupal
Version: 1.6.x, 2.0.0
Vulnerability: Forceful Browsing
Severity: Medium
date: 2026-05-19
Prediction: Patched May 2026
What Undercode Say:
Analytics
Check installed version of Node View Permissions
composer show drupal/node_view_permissions
List all nodes that may be vulnerable (requires DB access)
drush sqlq "SELECT nid, FROM node WHERE nid NOT IN (SELECT entity_id FROM node_access WHERE grant_view=1 AND realm='node_view_permissions')"
Simulate forceful browse attempt (replace example.com and NID)
curl -X GET "https://example.com/node/42?_format=json" -H "User-Agent: Mozilla/5.0" -I
Log analysis: detect repeated 200 OK on restricted nodes
grep "GET /node/[0-9]" /var/log/nginx/access.log | grep " 200 " | awk '{print $7}' | sort | uniq -c | sort -nr
Exploit:
Attacker sends crafted GET requests directly to node URLs with alternate formats (JSON, XML) or missing session cookies. Example: `https://target.com/node/1337?_wrapper_format=html`. If the response returns full node content (status 200) when anonymous user should be denied, the site is vulnerable. Mass exploitation uses a list of nid values from 1 to 10000.
Protection from this CVE
- Update to Node View Permissions 1.7.0 or 2.0.1 immediately.
- If cannot update, apply the following temporary fix in settings.php: `$settings[‘skip_permissions_hardening’] = FALSE;` and clear cache.
- Use a web application firewall (WAF) to block requests containing `_format` or `_wrapper_format` for node paths from anonymous users.
- Regularly audit node access records: `drush eval “print_r(node_access_view_all_nodes());”`
Impact:
Successful exploitation allows unauthorized users (including anonymous) to view any node’s , body, custom fields, and comments that were intended to be hidden. This leads to exposure of private content, business data, drafts, and potentially personally identifiable information (PII). Attackers can map the entire site’s content structure, escalating to further attacks like IDOR on referenced entities.
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Sources:
Reported By: nvd.nist.gov
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