CVE-2013-4170 in Ember.js
Summary
by MITRE • 06/30/2022
In general, Ember.js escapes or strips any user-supplied content before inserting it in strings that will be sent to innerHTML. However, the `tagName` property of an `Ember.View` was inserted into such a string without being sanitized. This means that if an application assigns a view's `tagName` to user-supplied data, a specially-crafted payload could execute arbitrary JavaScript in the context of the current domain ("XSS"). This vulnerability only affects applications that assign or bind user-provided content to `tagName`.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 07/17/2022
The vulnerability described in CVE-2013-4170 represents a critical cross-site scripting weakness within the Ember.js JavaScript framework that emerged from improper input sanitization practices. This flaw specifically targets the handling of user-supplied data within the view component architecture of Ember.js applications, where the framework typically employs robust escaping mechanisms to prevent malicious content from being executed in the browser context. The vulnerability stems from the inconsistent application of security controls, where Ember.js correctly sanitizes most user inputs before insertion into innerHTML operations but fails to apply the same protections to the tagName property of Ember.View components.
The technical implementation of this vulnerability occurs when developers assign user-provided content directly to the tagName property of Ember.View instances, creating a pathway for malicious input to bypass security measures. The tagName property, which determines the HTML tag type used for rendering views, becomes a vector for XSS attacks when it receives untrusted input without proper sanitization. This creates a scenario where attacker-controlled strings can be injected into HTML rendering contexts, allowing arbitrary JavaScript execution within the application's domain context. The vulnerability operates at the DOM manipulation layer where the framework constructs HTML elements, making it particularly dangerous as it can be exploited to steal session cookies, redirect users to malicious sites, or perform other malicious actions that compromise user security.
From an operational impact perspective, this vulnerability affects applications that implement dynamic view rendering with user-provided content, particularly those that allow user input to influence the structural elements of their web interfaces. The exploitation requires specific application patterns where user data is directly bound to view properties, making it less prevalent but more targeted in its impact. Security teams and developers must understand that this vulnerability demonstrates the importance of consistent security practices throughout application frameworks, as even well-protected components can become vulnerable when specific properties are overlooked in sanitization routines. The vulnerability aligns with CWE-79, which describes cross-site scripting flaws, and represents a classic case of context-dependent injection where proper sanitization should occur regardless of the input source or destination context.
The exploitation of this vulnerability follows established XSS attack patterns documented in the ATT&CK framework under the T1203 technique for "Exploitation for Client Execution," where attackers leverage application weaknesses to execute malicious code in the victim's browser. Applications that implement user registration, comment systems, or any feature allowing content customization that subsequently affects view rendering structures are particularly at risk. The remediation approach requires developers to ensure that all user-provided content assigned to the tagName property undergoes proper sanitization before being processed by the framework. This includes implementing input validation, output encoding, and potentially using framework-provided security mechanisms that automatically sanitize dynamic properties. Organizations should also consider adopting security development lifecycle practices that include comprehensive threat modeling and regular security code reviews to identify similar inconsistencies in other framework components.
This vulnerability serves as a reminder of the critical importance of maintaining consistent security controls across all application layers and components. The issue demonstrates how even mature frameworks can contain implementation gaps that require careful attention from both framework developers and application security teams. Proper mitigation involves not only patching the specific vulnerability but also establishing security policies that prevent similar issues from emerging in other parts of the application architecture. The incident highlights the need for automated security testing tools that can identify such context-specific vulnerabilities and the importance of security awareness training for developers working with modern web frameworks to ensure they understand the security implications of their code patterns.