CVE-2026-87948 in SAML SSO
Summary
by MITRE • 10/22/2026
Improper Neutralization of Input During Web Page Generation ("Cross-site Scripting") vulnerability in Drupal SAML SSO - Service Provider allows Cross-Site Scripting (XSS). This issue affects SAML SSO - Service Provider versions: from 0.0.0 to 3.2.0.
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Analysis
by VulDB Data Team • 10/22/2026
The identified vulnerability represents a classic instance of Improper Neutralization of Input During Web Page Generation, commonly known as Cross-Site Scripting or XSS within the context of web application security frameworks such as CWE-79. This specific flaw resides in the Drupal SAML SSO - Service Provider module, impacting all versions from 0.0.0 through 3.2.0. The core technical issue stems from insufficient validation and sanitization of user-controllable input before it is rendered within the HTML context of a web page. When an attacker crafts malicious script payloads and injects them into fields or parameters processed by this module, the application fails to escape special characters that have semantic meaning in HTML, such as angle brackets, quotes, and ampersands. Consequently, these scripts are executed directly by the victim's browser under the security context of the vulnerable Drupal site rather than being treated as inert data.
From an operational perspective, this vulnerability allows for a wide range of malicious activities depending on the privileges of the targeted user account. An attacker can execute arbitrary JavaScript code in the context of the affected domain, which facilitates session hijacking by stealing authentication cookies or tokens stored in browser storage. This capability enables the adversary to impersonate legitimate users without needing their credentials directly. Furthermore, the vulnerability supports keylogging capabilities where input fields are monitored for sensitive information such as passwords and personal data. It also allows for phishing attacks within the application interface, where fake login forms can be injected to trick users into revealing additional credentials or performing unintended actions that compromise system integrity.
The attack vector typically involves storing malicious scripts in database-backed fields accessible via the SAML authentication flow or manipulating query parameters during the service provider's handling of identity provider responses. This aligns with MITRE ATT&CK technique T1059, specifically sub-technique 007 for JavaScript execution, and often relates to CWE-83 regarding Stored XSS if the payload is persisted in the database before being served to other users. The severity of this vulnerability is heightened by its presence in a module dedicated to Single Sign-On operations, which are critical infrastructure components for enterprise access management. Compromise here can lead to broader lateral movement within an organization's network if session tokens provide access to multiple integrated services.
Mitigation strategies must prioritize immediate remediation through software updates. Administrators should upgrade the Drupal SAML SSO - Service Provider module to version 3.2.1 or any subsequent release where this input validation flaw has been addressed by properly encoding output data before it is inserted into HTML documents. In scenarios where an immediate patch cannot be applied, temporary mitigations include implementing strict Content Security Policy headers that restrict script execution sources and disable inline scripts using the nonce-based approach if supported by the browser environment. Additionally, deploying a Web Application Firewall with rules capable of detecting and blocking common XSS payload patterns can provide a layer of defense in depth while the underlying code is being corrected to ensure all user inputs are rigorously sanitized against HTML entity encoding standards before rendering.