CVE-2026-96359 in Webform
Summary
by MITRE • 10/22/2026
Improper Neutralization of Input During Web Page Generation ("Cross-site Scripting") vulnerability in Drupal Webform allows Cross-Site Scripting (XSS). This issue affects Webform versions: from 0.0.0 to 6.2.12, from 6.3.0 to 6.3.1.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 10/22/2026
The identified security flaw represents a classic instance of Improper Neutralization of Input During Web Page Generation, commonly known as Cross-Site Scripting or XSS within the Drupal Webform module ecosystem. This vulnerability specifically impacts versions ranging from the initial release up to 6.2.12 and subsequently from version 6.3.0 through 6.3.1. The core technical deficiency lies in the application's failure to adequately sanitize user-supplied input before rendering it within dynamic web pages. When a form is submitted, the data entered by users is processed and displayed back to them or other visitors without sufficient validation against executable script content. This lack of proper encoding allows attackers to inject malicious client-side scripts into the webpage context, which are then executed by the victim's browser under the trust relationship established with the vulnerable web application.
From a technical perspective, this vulnerability exploits the weak input handling mechanisms inherent in these specific versions of the Webform module. The flaw typically manifests when form submission data is reflected directly into HTML output without applying appropriate encoding functions such as htmlspecialchars or equivalent sanitization routines mandated by secure coding standards. An attacker can craft a specially designed HTTP request containing JavaScript code within one of the form fields. Upon successful submission, this malicious payload becomes part of the page's DOM structure. When another user views the affected page, their browser interprets and executes the injected script as if it were legitimate content from the trusted domain. This execution environment grants the attacker significant leverage to manipulate the client-side behavior of the application in real time.
The operational impact of this vulnerability is severe due to its potential for session hijacking, credential theft, and defacement. By executing arbitrary JavaScript within the context of the vulnerable site, an adversary can bypass same-origin policies that normally restrict how documents or scripts interact with resources from different origins. This capability enables the extraction of sensitive information such as session cookies, authentication tokens, and personally identifiable data stored in local storage or form fields. Furthermore, attackers may use this vector to perform actions on behalf of authenticated users without their knowledge, effectively compromising account integrity. In environments where administrative interfaces are accessible through similar forms, the risk escalates significantly, potentially leading to full system compromise if privileged accounts are targeted.
This vulnerability aligns with CWE-79, which categorizes Improper Neutralization of Input During Web Page Generation as a critical weakness in web application security frameworks. It also maps directly to MITRE ATT&CK technique T1059, specifically the sub-technique for JavaScript execution, illustrating how attackers leverage client-side scripting languages to achieve malicious objectives within browser sandboxes. The presence of this flaw indicates a gap in the input validation pipeline that fails to distinguish between safe data and executable code during the rendering phase.
To mitigate this risk, immediate action is required by upgrading the Drupal Webform module to a version beyond 6.3.1 where these sanitization issues have been addressed through rigorous code reviews and security patches. Administrators should ensure that all instances of user input are passed through robust output encoding functions before being rendered in HTML contexts. Implementing Content Security Policy headers can also provide an additional layer of defense by restricting the sources from which scripts can be loaded, thereby mitigating the impact even if some injection attempts succeed temporarily. Regular security audits and static code analysis tools should be employed to detect similar patterns across other modules within the Drupal installation to prevent broader exposure to client-side attacks.