CVE-2026-118575 in Signature Pad Widget
Summary
by MITRE • 10/30/2026
Improper Neutralization of Input During Web Page Generation ("Cross-site Scripting") vulnerability in Drupal Signature pad widget allows Stored XSS. This issue affects Signature pad widget versions: from 0.0.0 to 1.15.0.
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Analysis
by VulDB Data Team • 10/30/2026
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. Specifically, this vulnerability resides within the Signature pad widget module for Drupal, affecting all versions from 0.0.0 up to and including version 1.15.0. The core technical deficiency lies in the application's failure to adequately sanitize user-supplied input before it is rendered back into the web page context. When a user submits data through the signature pad interface, such as drawing a digital signature or entering associated metadata, the system fails to strip out malicious script tags or event handlers embedded within that payload. Consequently, when this untrusted data is subsequently displayed on other pages where the widget is utilized, the browser interprets the injected code as executable content rather than inert text. This behavior aligns directly with CWE-79, which categorizes vulnerabilities involving the improper neutralization of script-related HTML tags or attributes in web pages.
The operational impact of this stored XSS vulnerability is significant because it persists on the server side until explicitly removed by an administrator or through data cleanup processes. Unlike reflected XSS attacks that require tricking a user into clicking a malicious link, stored XSS allows an attacker to plant persistent scripts within the application's database. Any authenticated user who views content containing the injected payload will have their session compromised without any additional interaction beyond viewing the page. This can lead to severe consequences including account takeover via session hijacking, where the attacker steals the victim's authentication cookies or tokens. Furthermore, it enables credential harvesting if login forms are present on the same domain, and allows for defacement of the website by altering displayed content. In enterprise environments, this vulnerability can serve as an initial foothold for lateral movement within a network if the compromised session has elevated privileges.
From a threat intelligence perspective, this exploitation technique maps to several tactics in the MITRE ATT&CK framework. The act of injecting malicious scripts corresponds to Tactic TA0001 Initial Access or potentially TA0005 Defense Evasion depending on obfuscation techniques used. More critically, stealing session cookies and hijacking user sessions falls under Technique T1539 Steal Web Session Cookie within the Credential Access tactic. If the attacker uses the compromised account to perform actions such as modifying content or accessing sensitive data, it aligns with TA0042 Impact for defacement or TA0007 Discovery if reconnaissance is performed using the victim's privileges. The persistence of the payload means that even after the initial attack vector is patched, existing malicious entries in the database remain active until a remediation script clears them, extending the window of exposure significantly compared to non-persistent vulnerabilities.
Mitigation strategies must address both immediate containment and long-term prevention. For organizations running affected versions of the Signature pad widget, the primary recommendation is to upgrade immediately to version 1.15.1 or later where this input validation issue has been resolved by the maintainers. If upgrading is not immediately feasible due to compatibility constraints with other modules, a temporary workaround involves implementing strict output encoding using Drupal's built-in API functions such as check_plain() or filter_xss_admin() when rendering user-supplied data from the signature widget. Additionally, deploying a Web Application Firewall can provide an additional layer of defense by filtering out requests containing known XSS patterns before they reach the application logic. It is also crucial to review and sanitize existing database records that may contain previously injected malicious scripts to prevent ongoing exploitation against other users. Regular security audits and code reviews focusing on input validation practices are essential to preventing similar CWE-79 vulnerabilities in future development cycles.