CVE-2026-76759 Overview
CVE-2026-76759 is a cross-site scripting (XSS) vulnerability [CWE-79] affecting the Drupal Screenshot contributed module. The flaw allows an attacker to inject and execute malicious script content within the context of the Drupal application. Exploitation requires high-privilege access and user interaction, but a successful attack impacts resources beyond the vulnerable component due to a scope change. The issue affects Screenshot module versions as published in Drupal Security Advisory 2026-102.
Critical Impact
Successful exploitation permits script injection that compromises confidentiality and integrity of user sessions interacting with the affected Drupal site.
Affected Products
- Drupal Screenshot module (contributed)
- Drupal sites with the Screenshot module enabled
- Refer to Drupal Security Advisory 2026-102 for exact affected version ranges
Discovery Timeline
- 2026-09-02 - CVE-2026-76759 published to NVD
- 2026-09-02 - Last updated in NVD database
Technical Details for CVE-2026-76759
Vulnerability Analysis
The vulnerability is classified as Improper Neutralization of Input During Web Page Generation, commonly known as cross-site scripting [CWE-79]. The Screenshot module fails to properly sanitize or encode user-supplied input before rendering it in web page output. An authenticated attacker with elevated permissions can supply crafted input that is later reflected or stored in pages viewed by other users. When a victim loads the affected page, the injected script executes in the victim's browser under the trust context of the Drupal site.
The scope change indicated by the CVSS vector reflects that injected script can affect resources managed outside the immediate vulnerable component, including administrative interfaces and other authenticated sessions.
Root Cause
The root cause is missing or insufficient output encoding of user-controlled data handled by the Screenshot module. Drupal's rendering pipeline expects modules to pass untrusted data through filtering APIs such as \Drupal\Component\Utility\Html::escape() or render arrays using the #plain_text property. When a module bypasses these safeguards and emits raw markup, the browser interprets attacker-supplied HTML and JavaScript as legitimate page content.
Attack Vector
Exploitation requires network access to the Drupal application, high-level privileges to reach the vulnerable Screenshot module functionality, and user interaction from a victim who visits the crafted page. An attacker with permission to configure or submit content through the module injects a payload containing HTML script tags or event-handler attributes. When another user, typically an administrator, views the affected view or configuration page, the payload executes in their session.
The vulnerability is described in prose because no verified proof-of-concept code is publicly available. Consult the Drupal Security Advisory 2026-102 for vendor-supplied technical detail.
Detection Methods for CVE-2026-76759
Indicators of Compromise
- Unexpected <script> tags, on* event handlers, or javascript: URIs stored in Screenshot module configuration or output fields
- Web server access logs showing POST requests to Screenshot module endpoints containing encoded HTML or script payloads
- Anomalous administrative sessions initiating outbound requests to attacker-controlled domains shortly after viewing Screenshot-rendered pages
Detection Strategies
- Review Drupal watchdog and web server logs for requests to Screenshot module paths containing suspicious characters such as <, >, ", or URL-encoded equivalents
- Scan the database for stored Screenshot configuration entries containing script markup or unusual HTML fragments
- Deploy web application firewall rules that flag reflected and stored XSS payload patterns targeting Drupal module endpoints
Monitoring Recommendations
- Enable Content Security Policy (CSP) reporting to capture blocked inline script execution attempts
- Alert on unexpected privilege changes or administrative actions following visits to Screenshot module pages
- Correlate authenticated Drupal sessions with outbound network traffic to identify credential or session token exfiltration
How to Mitigate CVE-2026-76759
Immediate Actions Required
- Apply the security update referenced in Drupal Security Advisory 2026-102 to all Drupal sites running the Screenshot module
- Audit user roles and revoke Screenshot-related permissions from accounts that do not require them
- Review existing Screenshot module content and configuration for previously injected payloads and remove any malicious entries
Patch Information
Drupal published fix details in Drupal Security Advisory 2026-102. Site operators should upgrade the Screenshot contributed module to the fixed version identified in the advisory. Verify the module version after upgrade using drush pm:list --type=module or the Drupal administrative interface.
Workarounds
- Disable the Screenshot module until the patched version can be installed
- Restrict access to Screenshot module configuration to a minimal set of trusted administrators
- Enforce a strict Content Security Policy that disallows inline scripts and unsafe evaluation to reduce XSS impact
# Disable and uninstall the Screenshot module until patched
drush pm:uninstall screenshot
# After patching, update and re-enable
composer update drupal/screenshot
drush pm:enable screenshot
drush cache:rebuild
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
