CVE-2026-4418 in Cloud Pak System
Summary
by MITRE • 10/19/2026
IBM Cloud Pak System 2.3.6.0, and 2.3.6.1 is vulnerable to HTML injection. A remotely authenticated attacker could inject malicious HTML code, which when viewed, would be executed in the victim's Web browser within the security context of the hosting site.
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Analysis
by VulDB Data Team • 10/19/2026
IBM Cloud Pak System versions 2.3.6.0 and 2.3.6.1 contain a critical input validation flaw that allows for HTML injection attacks against remotely authenticated users. This vulnerability arises from insufficient sanitization or encoding of user-supplied data within the application's web interface, specifically in components where user input is rendered directly into the Document Object Model without proper context-aware escaping. When an attacker successfully injects malicious HTML code through these vulnerable inputs, the browser interprets and executes this content as part of the legitimate page structure rather than treating it as inert text. This execution occurs within the security context of the hosting site, meaning that any scripts or embedded elements run with the same privileges and permissions as the original application, effectively bypassing standard cross-origin restrictions designed to isolate web applications from untrusted sources.
The operational impact of this vulnerability is significant because it enables a wide range of client-side attacks against authenticated users of the IBM Cloud Pak System platform. Since the attack requires remote authentication, an attacker must first compromise valid credentials or exploit other vulnerabilities to gain access before they can trigger the injection. Once inside, the ability to inject HTML allows for sophisticated social engineering campaigns where attackers can craft deceptive login forms, phishing pages, or misleading alerts that appear legitimate because they are hosted on the trusted domain of IBM Cloud Pak System. This trust exploitation increases the likelihood of user interaction with malicious content, potentially leading to credential theft via keyloggers embedded in the injected HTML or session hijacking through cookie access if appropriate security headers like HttpOnly are not strictly enforced across all application endpoints.
From a technical classification perspective, this flaw aligns closely with CWE-80, which covers Improper Neutralization of Script-Related HTML Tags in a Web Page, and often overlaps with CWE-79, the more general category for Cross-Site Scripting (XSS). The specific mechanism described here focuses on HTML injection rather than pure script execution, but in modern browsers, injected HTML frequently contains JavaScript event handlers or iframe elements that facilitate full XSS payloads. In terms of offensive security frameworks, this vulnerability maps to MITRE ATT&CK technique T1059.007, which involves Command and Scripting Interpreter via Browser-based Execution, specifically under the sub-technique for Web Protocols. The attack vector is classified as Remote with Authentication required, placing it in a lower initial complexity category compared to unauthenticated XSS but still posing a severe risk due to the high privilege level of authenticated users within cloud management platforms.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. IBM has released updated versions that patch this input validation deficiency by implementing strict output encoding and context-aware escaping for all user-controlled data rendered in HTML contexts. Organizations running version 2.3.6.0 or 2.3.6.1 should prioritize upgrading to the latest patched release immediately to eliminate the attack surface. In addition to applying vendor patches, administrators should enforce Content Security Policy headers that restrict script execution and frame sources, thereby limiting the damage even if an injection attempt succeeds. Furthermore, implementing robust input validation on both client-side and server-side layers ensures that only expected data formats are processed, reducing the risk of unexpected HTML structures being introduced into the application flow. Regular security audits focusing on web application firewall rules can also help detect and block attempts to inject malicious markup before it reaches vulnerable endpoints.