CVE-2026-44767 in webcomponents-base
Summary
by MITRE • 07/14/2026
setThemeRoot() failed to enforce the sap-allowed-theme-origins allowlist. An attacker-controlled absolute cross-origin URL could be stored and used directly to construct a <link rel=stylesheet> element, even when no <meta name=sap-allowed-theme-origins> tag was present in the document. The same bypass was reachable via the ?sap-themeRoot URL parameter.Exploitation requires attacker-influenced input (e.g., a URL query parameter, tenant configuration, or user-supplied setting) to reach setThemeRoot(). A successful exploit allows an attacker to inject arbitrary CSS into the victim page, enabling:- UI redressing and clickjacking- Phishing overlays- Visual defacement- Limited data exfiltration via CSS attribute selectors targeting predictable DOM content
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Analysis
by VulDB Data Team • 07/14/2026
The vulnerability described represents a critical security flaw in SAP application frameworks related to theme management and cross-origin resource handling. This issue stems from inadequate enforcement of the sap-allowed-theme-origins allowlist mechanism within the setThemeRoot() function, creating a pathway for malicious actors to bypass intended security controls. The flaw demonstrates a classic case of insufficient input validation and origin restriction enforcement that directly impacts the application's security boundaries.
The technical implementation of this vulnerability occurs when an attacker-controlled absolute cross-origin URL is processed through the setThemeRoot() function without proper validation against the allowed origins list. This allows arbitrary URLs to be stored and subsequently used to construct HTML elements, specifically CSS link tags, even in scenarios where no initial tag structure exists within the document. The bypass mechanism operates through both direct URL parameter manipulation and the ?sap-themeRoot URL parameter, providing multiple attack vectors for exploitation. The vulnerability essentially transforms a controlled configuration parameter into an arbitrary resource injection point.
The operational impact of this vulnerability extends beyond simple CSS injection, creating substantial risks for user interface security and data protection. Attackers can leverage this flaw to implement UI redressing and clickjacking attacks by injecting malicious CSS that overlays legitimate application interfaces, making users believe they are interacting with trusted elements while actually performing actions for the attacker. Phishing overlays become possible through carefully crafted CSS that mimics legitimate application interfaces, potentially capturing user credentials or sensitive information. Visual defacement capabilities allow attackers to alter the appearance of applications, undermining user trust and potentially obscuring critical security warnings.
The attack requirements for successful exploitation necessitate that an attacker control input parameters that influence the setThemeRoot() function execution path. This typically involves manipulating URL query parameters, tenant configurations, or user-supplied settings that eventually reach the vulnerable function. The vulnerability aligns with CWE-20: Improper Input Validation and represents a specific instance of insecure direct object reference patterns where cross-origin resource handling is improperly constrained. From an attack framework perspective, this vulnerability maps to techniques described in the ATT&CK matrix under T1546.003: Create or Modify System Process - Windows Service and T1566.001: Phishing - Spearphishing Attachment, as it enables both system-level interface manipulation and user deception through visual means.
Mitigation strategies should focus on strengthening origin validation mechanisms within the theme management system, implementing comprehensive input sanitization for all URL parameters, and enforcing strict CSP (Content Security Policy) headers that restrict CSS loading from untrusted origins. The solution requires implementing robust allowlist validation for all cross-origin resource references, particularly those related to theme origins, and ensuring that no attacker-controlled input can bypass these security controls. Organizations should also consider implementing additional runtime checks that monitor for unexpected CSS injection patterns and establish comprehensive logging of theme-related configuration changes to detect potential exploitation attempts.