CVE-2026-24732: BlueSpice Auth Bypass Vulnerability

CVE-2026-24732 Overview

CVE-2026-24732 is an access control vulnerability in Hallo Welt! GmbH BlueSpice, specifically affecting the Extension:NSFileRepo modules. The vulnerability involves files or directories being accessible to external parties due to incorrect permission assignment for critical resources. This flaw enables attackers to access functionality not properly constrained by Access Control Lists (ACLs) and bypass electronic locks and access controls.

Critical Impact

Unauthorized access to protected files and directories in BlueSpice MediaWiki installations could lead to sensitive information disclosure and circumvention of security controls designed to protect critical resources.

Affected Products

• BlueSpice MediaWiki versions 5.1 through 5.1.3
• BlueSpice MediaWiki versions 5.2 through 5.2.0
• Extension:NSFileRepo versions 3.0 through 3.0.4

Discovery Timeline

• 2026-03-04 - CVE CVE-2026-24732 published to NVD
• 2026-03-04 - Last updated in NVD database

Technical Details for CVE-2026-24732

Vulnerability Analysis

This vulnerability stems from improper access control implementation in the NSFileRepo extension for BlueSpice MediaWiki. The NSFileRepo extension is designed to provide namespace-based file repository functionality, allowing administrators to organize and restrict access to files within specific namespaces. However, due to flawed permission checks, external parties can access files and directories that should be protected by ACL restrictions.

The weakness is classified under CWE-552 (Files or Directories Accessible to External Parties), which describes scenarios where application logic fails to properly restrict access to files and directories that should be protected. In this case, the extension does not adequately enforce the configured access controls, allowing unauthorized users to retrieve files that should be restricted to specific user groups or namespaces.

Root Cause

The root cause of this vulnerability lies in the incorrect permission assignment logic within the NSFileRepo module. When processing file access requests, the extension fails to properly validate whether the requesting user has appropriate ACL permissions to access the requested resource. This results in a condition where the ACL enforcement mechanism can be bypassed, exposing protected files to unauthorized parties.

Attack Vector

The vulnerability is exploitable over the network without requiring authentication or user interaction. An attacker can craft requests to access files within protected namespaces by directly targeting the NSFileRepo endpoints. Since the permission validation is flawed, these requests may succeed even when the attacker lacks the necessary ACL permissions to access the targeted resources.

The attack allows unauthorized read access to potentially sensitive files stored in protected namespaces within the BlueSpice MediaWiki installation. This could include internal documentation, confidential files, or other sensitive content that organizations have attempted to protect using namespace-based access controls.

Detection Methods for CVE-2026-24732

Indicators of Compromise

• Unusual access patterns to files within protected namespaces from unauthenticated or unauthorized users
• HTTP requests targeting NSFileRepo endpoints from external IP addresses without proper session credentials
• Increased file download activity from namespace-protected directories by users who should not have access

Detection Strategies

• Monitor web server access logs for requests to NSFileRepo module endpoints, particularly from unauthenticated sessions
• Implement alerting for access attempts to protected namespaces that do not match expected user permission profiles
• Deploy web application firewall rules to detect and log suspicious access patterns targeting file repository functionality

Monitoring Recommendations

• Enable detailed access logging for the BlueSpice MediaWiki installation, specifically for file access operations
• Configure SIEM integration to correlate access attempts with user authentication status and ACL configurations
• Establish baseline metrics for normal file access patterns to identify anomalous activity

How to Mitigate CVE-2026-24732

Immediate Actions Required

• Upgrade BlueSpice MediaWiki to version 5.1.4 or 5.2.1 or later
• Upgrade Extension:NSFileRepo to version 3.0.5 or later
• Review access logs to identify any potential unauthorized access to protected files prior to patching
• Audit file permissions and ACL configurations to ensure they align with intended access policies

Patch Information

Hallo Welt! GmbH has released security updates to address this vulnerability. Organizations should upgrade to BlueSpice MediaWiki version 5.1.4 or later (for the 5.1.x branch) or version 5.2.1 or later (for the 5.2.x branch). For organizations managing the NSFileRepo extension separately, upgrade to version 3.0.5 or later. Detailed patch information is available in the BlueSpice Security Advisory BSSA-2026-02.

Workarounds

• Temporarily disable the NSFileRepo extension if it is not critical to operations until the patch can be applied
• Implement additional network-level access controls to restrict access to the BlueSpice installation to trusted IP ranges
• Configure web server rules to block direct access to NSFileRepo endpoints from unauthenticated users as an interim measure