CVE-2026-55808 in Drupal
Summary
by MITRE • 07/11/2026
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 0.0.0 to 10.5.12, from 10.6.0 to 10.6.11, from 11.2.0 to 11.2.14, from 11.3.0 to 11.3.12, from 0.0.0 to 11.0.*, from 0.0.0 to 11.1.*.
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Analysis
by VulDB Data Team • 07/11/2026
Cross-site scripting vulnerabilities represent one of the most prevalent and dangerous web application security flaws, with Drupal's implementation suffering from improper input neutralization during web page generation processes that creates exploitable entry points for malicious actors. This vulnerability falls under the established CWE-79 category known as "Improper Neutralization of Input During Web Page Generation" which specifically addresses situations where applications fail to properly sanitize user-provided data before incorporating it into dynamically generated web content. The flaw manifests when Drupal core processes user input through various mechanisms including form submissions, URL parameters, or API endpoints without adequate sanitization protocols that would normally neutralize potentially harmful script code.
The technical nature of this vulnerability stems from the failure to implement proper output encoding and input validation measures within Drupal's core rendering engine, particularly affecting versions across multiple release branches including 10.x series up to 10.5.12, 10.6.0 through 10.6.11, 11.2.0 through 11.2.14, 11.3.0 through 11.3.12, and all versions up to 11.0. and 11.1.. When malicious actors exploit this weakness, they can inject arbitrary javascript code into web pages that are then executed in the browsers of unsuspecting users who visit affected pages. The vulnerability operates by bypassing Drupal's built-in security measures that should normally prevent untrusted input from being rendered as executable code within the browser context. This creates a persistent threat vector where attackers can hijack user sessions, steal sensitive information, perform unauthorized actions on behalf of victims, or redirect users to malicious websites.
The operational impact of this vulnerability extends beyond simple script execution to encompass significant risks for organizations relying on Drupal platforms, particularly in environments where administrative privileges are compromised or where sensitive data flows through the affected application components. Attackers can leverage this weakness to establish persistent backdoors, conduct session hijacking attacks, or execute more sophisticated exploits that combine with other vulnerabilities to escalate privileges within the web application environment. The breadth of affected versions indicates a fundamental flaw in Drupal's input handling mechanisms that spans multiple major releases, suggesting that organizations running any of these vulnerable versions face immediate risk of exploitation. Security researchers and threat actors have documented numerous real-world exploitation attempts against similar XSS vulnerabilities in content management systems, making this particular weakness highly attractive for malicious actors seeking to compromise Drupal installations.
Organizations should implement immediate mitigations including applying the latest security patches released by the Drupal project, which typically involve enhanced input validation routines and proper output encoding mechanisms that prevent script code from being executed in browser contexts. Additionally, implementing web application firewalls with XSS detection capabilities, enforcing strict Content Security Policy headers, and conducting regular security assessments of all user-facing interfaces can provide additional protective layers. The ATT&CK framework categorizes such vulnerabilities under T1203 - Exploitation for Client Execution, with specific techniques including T1566 - Phishing for Information and T1190 - Exploit Public-Facing Application, highlighting the multi-layered nature of attacks that can exploit this class of vulnerability. Security teams should also consider implementing automated monitoring solutions to detect unusual patterns in user input or application behavior that might indicate exploitation attempts against known XSS vectors within their Drupal deployments.