CVE-2026-87949 in SAML SSO
Summary
by MITRE • 10/23/2026
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.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/23/2026
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 Drupal SAML SSO Service Provider module. This security flaw exists in versions ranging from 0.0.0 to 3.2.0 and stems from insufficient validation and sanitization of user-supplied input before it is rendered into HTML output by the web application. In this specific context, the vulnerability likely arises when data retrieved from SAML assertions or related authentication flows is processed without adequate encoding, allowing malicious scripts to be injected into the page content served to legitimate users. The core technical flaw lies in the failure of the module to properly escape special characters such as angle brackets, quotes, and ampersands that have semantic meaning in HTML and JavaScript contexts. When an attacker crafts a specially formatted SAML response or manipulates parameters associated with the authentication process, they can inject executable client-side code into the victim's browser session.
From an operational perspective, this vulnerability poses significant risks to both end-users and system administrators who rely on single sign-on capabilities for secure access management. Successful exploitation allows attackers to execute arbitrary JavaScript in the context of the affected Drupal site, which typically runs with elevated privileges relative to standard user scripts due to its execution within authenticated sessions or administrative interfaces depending on the specific vector utilized. This capability enables a range of malicious activities including session hijacking through theft of cookies and authentication tokens, credential harvesting by mimicking legitimate login forms via phishing overlays, defacement of web pages, and redirection of users to malicious external sites designed for further exploitation such as malware distribution or social engineering attacks. The impact is particularly severe in enterprise environments where SAML integration is critical for identity federation across multiple systems, as compromising the integrity of this trust chain can lead to broader lateral movement within the network infrastructure.
This vulnerability aligns with CWE-79, which categorizes Improper Neutralization of Input During Web Page Generation: Cross-site Scripting, highlighting the fundamental failure in input handling mechanisms that are essential for web application security. Furthermore, from a tactical standpoint related to adversary behavior frameworks such as MITRE ATT&CK, this flaw facilitates techniques associated with Client-Side Injection and potentially Credential Access through phishing if used to steal credentials during authentication flows. The attack vector often involves Stored or Reflected XSS depending on whether the malicious payload is persisted in the database via SAML attributes or delivered dynamically within a single request-response cycle. Attackers can leverage browser-based tools and automated scripts to exploit this weakness, making it accessible even to individuals with limited technical expertise once they understand how to manipulate the SAML assertion parameters sent during the authentication handshake.
Mitigation strategies must prioritize immediate remediation through software updates as well as defensive configuration changes for environments where upgrading is not immediately feasible. The primary recommendation is to upgrade the Drupal SAML SSO Service Provider module to version 3.2.1 or later, which includes patches addressing these input validation deficiencies and ensures proper encoding of all dynamic content before rendering in HTML contexts. For organizations unable to patch immediately due to compatibility constraints with other integrated systems, implementing a Web Application Firewall can provide an additional layer of defense by filtering out requests containing known XSS payloads within SAML parameters. Additionally, enforcing strict Content Security Policy headers that restrict the execution of inline scripts and limit script sources to trusted domains can significantly reduce the impact of any successful injection attempts. Regular security audits focusing on input validation logic in authentication modules are also advised to prevent similar vulnerabilities from arising in future updates or custom integrations involving SAML protocols.