CVE-2026-108514 in Drupal
Summary
by MITRE • 10/30/2026
Improper Neutralization of Input During Web Page Generation ("Cross-site Scripting") vulnerability in Drupal Drupal core allows Cross-Site Scripting (XSS). This issue affects Drupal core versions: from 10.3.0 to 10.6.19, from 11.0.0 to 11.3.19, from 11.4.0 to 11.4.10, from 12.0.0-alpha1 to 12.0.0-beta2.
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Analysis
by VulDB Data Team • 10/30/2026
The identified vulnerability represents a critical security flaw within the Drupal core software ecosystem, specifically classified as an Improper Neutralization of Input During Web Page Generation, commonly known as Cross-Site Scripting or XSS. This category of weakness is formally defined under CWE-79 in the Common Weakness Enumeration standard, indicating that the application fails to properly validate, sanitize, or encode user-supplied input before including it in dynamically generated web pages. In the context of Drupal, a widely used content management system powering millions of websites globally, such a flaw allows attackers to inject malicious client-side scripts into webpages viewed by other users. The vulnerability impacts multiple major branches and versions of Drupal core, specifically affecting releases from 10.3.0 through 10.6.19, as well as the newer development lines including 11.0.0 to 11.3.19, 11.4.0 to 11.4.10, and pre-release versions such as 12.0.0-alpha1 through beta2. This broad scope underscores a systemic issue in how input handling mechanisms were implemented across these specific version ranges.
From a technical perspective, the root cause lies in the failure of Drupal's rendering pipeline to adequately escape special characters or strip executable script tags when processing user-generated content that is subsequently displayed on public-facing pages. When an attacker crafts a malicious payload containing JavaScript code and submits it through any input vector accessible within these vulnerable versions—such as comment fields, profile descriptions, or custom form inputs—the server processes the request without applying sufficient security filters. Consequently, the browser interprets the injected script as legitimate content belonging to the site's domain. This execution environment is particularly dangerous because browsers enforce a same-origin policy that trusts scripts originating from the current page context, thereby granting the malicious code full access to cookies, session tokens, and local storage associated with the victim’s authenticated session on the Drupal instance.
The operational impact of this vulnerability extends beyond simple defacement or visual disruption. Attackers can leverage Cross-Site Scripting for a variety of hostile activities aligned with MITRE ATT&CK technique T1059.007, which covers JavaScript execution. By stealing authentication cookies and session identifiers, an attacker can hijack user sessions to impersonate legitimate administrators or end-users without needing their passwords. This capability facilitates unauthorized access to sensitive administrative panels, allowing for the modification of site configuration, extraction of database contents, or further exploitation through privilege escalation. Furthermore, XSS payloads can be used to perform actions on behalf of the victim, such as changing email addresses associated with accounts, initiating financial transactions if e-commerce modules are present, or redirecting users to phishing sites designed to harvest credentials from unsuspecting visitors.
Mitigation strategies must prioritize immediate remediation by upgrading Drupal core to a version that includes patches for this specific input neutralization flaw. Administrators should consult the official Drupal security advisories corresponding to their current installation branch and apply the latest available updates, which typically involve code changes in the rendering layer or form API components responsible for output encoding. In scenarios where immediate patching is not feasible due to dependency constraints or testing requirements, temporary compensating controls can be implemented at the web server level using Web Application Firewalls that detect and block common XSS patterns in HTTP request parameters. Additionally, enforcing strict Content Security Policy headers can significantly reduce the impact of successful injection attempts by restricting the sources from which scripts are allowed to execute, thereby limiting the effectiveness of any injected payloads even if they bypass initial input validation checks.