CVE-2026-81166 Overview
CVE-2026-81166 is a Missing Authorization vulnerability [CWE-862] in the Drupal Digital Signage Framework contributed module. The flaw allows unauthenticated attackers to perform forceful browsing against restricted endpoints. Affected versions span from 0.0.0 through 2.6.1 of the Digital Signage Framework module for Drupal.
The vulnerability exposes information that should be gated behind proper access controls. Exploitation requires network access to the Drupal site but no authentication or user interaction. According to the Drupal Security Advisory SA-2026-109, site administrators should upgrade to a fixed release.
Critical Impact
Unauthenticated network attackers can access resources intended to be restricted, resulting in limited confidentiality impact on affected Drupal sites.
Affected Products
- Drupal Digital Signage Framework module versions 0.0.0 through 2.6.1
- Drupal sites with the Digital Signage Framework contributed module enabled
- Any Drupal deployment relying on the module's access control for restricted content
Discovery Timeline
- 2026-09-02 - CVE-2026-81166 published to the National Vulnerability Database (NVD)
- 2026-09-02 - Last updated in NVD database
Technical Details for CVE-2026-81166
Vulnerability Analysis
The Digital Signage Framework module fails to perform authorization checks on one or more routes or resources. This class of flaw, categorized as [CWE-862] Missing Authorization, occurs when application code exposes functionality without validating that the requesting user holds the required permissions.
Because the check is missing rather than merely weak, an attacker does not need to bypass logic, forge tokens, or escalate privileges. Direct HTTP requests to the affected paths return data that should be gated. The attack vector is network-based and requires no privileges or user interaction.
The advisory characterizes the exploitation technique as forceful browsing, meaning attackers enumerate or guess URLs to reach unlinked or unadvertised resources. The impact is scoped to confidentiality; integrity and availability are not affected according to the published CVSS vector.
Root Cause
The module code path serving the affected resource does not invoke Drupal's access control APIs, such as route _permission or _access requirements, or omits equivalent programmatic checks in a controller or hook. As a result, anonymous requests reach handler code that returns protected content.
Attack Vector
An unauthenticated remote attacker sends crafted HTTP requests directly to the vulnerable module routes. No authentication credentials, tokens, or session state are required. Successful exploitation returns information intended for authorized users only. No verified proof-of-concept code has been published, and the vulnerability is not listed on the CISA Known Exploited Vulnerabilities catalog.
See the Drupal Security Advisory SA-2026-109 for vendor-supplied technical details.
Detection Methods for CVE-2026-81166
Indicators of Compromise
- Anonymous HTTP GET requests to Digital Signage Framework module paths returning HTTP 200 with content payloads instead of 403 responses
- Unusual enumeration patterns against Drupal routes associated with the module from a single source address
- Access log entries showing successful responses to restricted module endpoints without preceding authentication events
Detection Strategies
- Review Drupal access logs and web server logs for anonymous access to module-controlled routes that should require authenticated sessions
- Correlate response codes and content-length values on module endpoints to identify successful unauthorized retrieval
- Run authenticated vulnerability scans against Drupal sites to enumerate installed contributed modules and flag Digital Signage Framework versions at or below 2.6.1
Monitoring Recommendations
- Alert on repeated anonymous requests to Drupal admin-adjacent or module-restricted paths from the same IP
- Track the installed module inventory across Drupal deployments and flag versions matching the vulnerable range
- Forward web server and Drupal watchdog logs to a centralized analytics platform for retrospective hunting on module endpoints
How to Mitigate CVE-2026-81166
Immediate Actions Required
- Identify all Drupal sites running the Digital Signage Framework contributed module at version 2.6.1 or earlier
- Upgrade the module to the fixed release identified in the Drupal Security Advisory SA-2026-109
- Audit web server access logs for prior anonymous access to affected module routes
Patch Information
Drupal has published guidance under advisory SA-2026-109 covering the Digital Signage Framework module. Site operators should upgrade to a fixed version above 2.6.1 as directed in the advisory. Clear the Drupal cache after applying the update to ensure route definitions and access checks are rebuilt.
Workarounds
- Disable the Digital Signage Framework module until the fixed version can be deployed if patching is not immediately possible
- Restrict access to Drupal site paths associated with the module using a web application firewall or upstream reverse proxy access control rules
- Require authentication at the web server or CDN layer for module routes as a compensating control until the upgrade is completed
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
