CVE-2026-88060 in Angular
Summary
by MITRE • 09/10/2026
Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to 20.3.30, 21.2.22, and 22.1.4, Angular server-side rendering (SSR) in @angular/platform-server serializes untrusted input inside template content nested in fallback raw-content elements such as noscript, iframe, noembed, and noframes. The Domino serializer's fallbackRawContentTags traversal stopped at the DocumentFragment used by template.content, so matching closing tags in xmp, style, script, comments, or text nodes were not escaped. Standard interpolation with comments or text nodes is reachable without relaxed schemas; literal xmp or style requires CUSTOM_ELEMENTS_SCHEMA or NO_ERRORS_SCHEMA, while Renderer2 imperative DOM construction is unconditionally affected. When HTML5 RAWTEXT browser parsing encounters the unescaped closing tag, it exits the fallback container and interprets trailing markup as active DOM elements, enabling arbitrary JavaScript execution. This issue is fixed in versions 20.3.30, 21.2.22, and 22.1.4.
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Analysis
by VulDB Data Team • 09/10/2026
Angular serves as a comprehensive development platform for constructing mobile and desktop web applications using TypeScript or JavaScript. A critical security vulnerability exists within the server-side rendering (SSR) implementation of Angular in versions prior to 20.3.30, 21.2.22, and 22.1.4. This flaw specifically affects how untrusted input is serialized when it resides inside template content that is nested within fallback raw-content HTML elements such as noscript, iframe, noembed, and noframes. The core technical deficiency lies in the behavior of the Domino serializer used by Angular for server-side rendering operations. When processing these specific DOM structures, the serializer's logic for handling fallback raw content tags fails to properly traverse or escape closing tags found within xmp elements, style blocks, script tags, HTML comments, or plain text nodes that are part of a DocumentFragment associated with template.content.
The operational impact of this vulnerability is severe because it allows an attacker to bypass standard security boundaries and achieve arbitrary JavaScript execution on the client side. Under normal circumstances, Angular's interpolation mechanism provides protection against cross-site scripting by escaping special characters. However, in the context described above, if untrusted data contains closing tags for raw text elements or comments that are not properly escaped due to the serializer bug, these tags remain intact in the final HTML output sent to the browser. When an HTML5-compliant browser parses this response, it encounters the unescaped closing tag within a RAWTEXT content mode context. This causes the browser to exit the fallback container prematurely and interpret any subsequent trailing markup as active DOM elements rather than inert text. Consequently, if that trailing markup includes executable script tags or event handlers, they will be executed by the user's browser, leading to a successful cross-site scripting attack.
The exploitability of this vulnerability varies depending on how the Angular application is configured and constructed. Standard interpolation with comments or text nodes can trigger this issue without requiring any relaxed schema configurations. However, for scenarios involving literal xmp or style elements within templates, developers typically need to utilize CUSTOM_ELEMENTS_SCHEMA or NO_ERRORS_SCHEMA to bypass strict template validation rules. In contrast, when using Renderer2 for imperative DOM construction, the vulnerability is unconditionally present regardless of schema settings because the underlying serialization logic does not differentiate based on these higher-level configuration flags. This makes the flaw particularly dangerous in applications that dynamically construct complex UI components server-side without rigorous input sanitization protocols.
From a classification perspective, this vulnerability aligns with CWE-79, which covers Improper Neutralization of Input During Web Page Generation known as Cross-site Scripting (XSS). Specifically, it represents an XSS issue arising from improper handling of raw text content in HTML parsing contexts. In terms of the MITRE ATT&CK framework for web applications, this flaw facilitates techniques associated with Client-Side Injection and potentially Stored or Reflected XSS depending on whether the vulnerable input is persisted server-side or passed directly via request parameters. The failure to escape closing tags effectively neutralizes one layer of Angular's built-in defense mechanisms, allowing attackers to inject malicious payloads that bypass standard output encoding expectations.
To mitigate this risk, organizations must upgrade their Angular dependencies immediately to version 20.3.30, 21.2.22, or 22.1.4 and later releases where the Domino serializer has been patched to correctly escape these specific closing tags within fallback raw content contexts. For applications that cannot be upgraded instantly, developers should implement rigorous input validation and output encoding strategies for any data rendered inside noscript, iframe, noembed, or noframes elements during server-side rendering. It is also advisable to audit codebases using Renderer2 imperative DOM construction methods to ensure that untrusted inputs are not being inserted into these vulnerable structural contexts without additional sanitization layers. Regular security assessments focusing on SSR implementations and template injection vectors should be conducted to identify similar serialization flaws in other frameworks or custom rendering logic.