CVE-2026-0944: Drupal Group Invite Auth Bypass Flaw

CVE-2026-0944 Overview

CVE-2026-0944 is an Improper Check for Unusual or Exceptional Conditions vulnerability (CWE-754) affecting the Drupal Group invite module. This security flaw allows attackers to perform Forceful Browsing attacks, potentially gaining unauthorized access to restricted group invitation functionality within Drupal-based websites.

The vulnerability stems from inadequate validation of exceptional conditions in the Group invite module, enabling unauthenticated attackers to bypass intended access restrictions and access resources that should require proper authorization.

Critical Impact

Unauthenticated attackers can exploit this vulnerability via network access to access sensitive group invitation data or functionality without proper authorization, potentially leading to information disclosure.

Affected Products

• Drupal Group invite versions 0.0.0 through 2.3.8 (fixed in 2.3.9)
• Drupal Group invite versions 3.0.0 through 3.0.3 (fixed in 3.0.4)
• Drupal Group invite versions 4.0.0 through 4.0.3 (fixed in 4.0.4)

Discovery Timeline

• 2026-02-04 - CVE CVE-2026-0944 published to NVD
• 2026-02-05 - Last updated in NVD database

Technical Details for CVE-2026-0944

Vulnerability Analysis

This vulnerability is classified under CWE-754 (Improper Check for Unusual or Exceptional Conditions). The Drupal Group invite module fails to properly validate edge cases or unusual conditions when processing requests, allowing attackers to perform Forceful Browsing attacks.

Forceful Browsing occurs when an attacker directly accesses URLs or resources that should be restricted, bypassing normal navigation flows and access controls. In this case, the Group invite module does not adequately verify that requests are coming through expected paths or that users have appropriate permissions for the requested resources.

The vulnerability is exploitable remotely over the network without requiring any authentication or user interaction, making it a concern for any Drupal site running the affected Group invite module versions.

Root Cause

The root cause lies in the insufficient validation logic within the Drupal Group invite module. The module fails to implement proper checks for unusual or exceptional conditions when handling group invitation requests. This allows attackers to craft requests that bypass the intended access control mechanisms, directly accessing invitation-related functionality or data without proper authorization checks being enforced.

Attack Vector

The attack vector is network-based, requiring no privileges or user interaction. An attacker can exploit this vulnerability by:

1. Identifying a Drupal website running a vulnerable version of the Group invite module
2. Crafting direct requests to group invitation endpoints that should normally require authorization
3. Bypassing intended access controls through Forceful Browsing techniques
4. Accessing group invitation data or functionality without proper authentication

The vulnerability allows unauthorized read access to potentially sensitive information, though it does not enable data modification or system disruption.

Detection Methods for CVE-2026-0944

Indicators of Compromise

• Unusual access patterns to group invitation URLs from unauthenticated sessions
• Direct requests to group invite endpoints bypassing normal application flow
• HTTP 200 responses to group invitation pages from sessions without proper group membership
• Anomalous traffic patterns targeting /group/*/invites or similar Group invite module paths

Detection Strategies

• Monitor web server access logs for direct requests to Group invite module endpoints from unauthenticated users
• Implement Web Application Firewall (WAF) rules to detect and alert on Forceful Browsing patterns targeting Drupal group functionality
• Review Drupal watchdog logs for unauthorized access attempts to group invitation features
• Deploy anomaly detection to identify requests that bypass normal navigation paths to reach restricted group invite resources

Monitoring Recommendations

• Enable verbose logging for the Group invite module to capture access patterns
• Configure alerts for repeated access attempts to group invitation pages from unknown or unauthenticated sources
• Monitor for enumeration patterns that may indicate attackers probing for accessible group invitations
• Implement rate limiting on group invitation endpoints to slow potential exploitation attempts

How to Mitigate CVE-2026-0944

Immediate Actions Required

• Upgrade Drupal Group invite module to patched versions: 2.3.9, 3.0.4, or 4.0.4 depending on your current major version
• Review web server logs for any signs of prior exploitation attempts
• Audit current group invitation data for any unauthorized access or disclosure
• Temporarily disable the Group invite module if immediate patching is not possible

Patch Information

Drupal has released security patches for all affected version branches. Administrators should update to the following fixed versions:

For detailed patch information, refer to the Drupal Security Advisory.

Workarounds

• Temporarily disable the Group invite module until patching can be performed
• Implement WAF rules to restrict direct access to group invitation endpoints
• Configure reverse proxy rules to require authentication for all Group invite module routes
• Limit access to group functionality to authenticated and authorized users only through server-level access controls

# Drupal module update via Composer
composer update drupal/group_invite

# Clear Drupal cache after update
drush cr

# Verify installed version
drush pm:list --filter=group_invite