@angular/platform-server: Missing `<noscript>` Raw-Text Serialization Escaping leads to Cross-Site Scripting (XSS) in Angular SSR
Date: 2026-06
Affected: npm/@angular/platform-server, npm/@angular/platform-server, npm/@angular/platform-server
Attack vector: xss
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2026-50556
CWE: CWE-79

A Cross-Site Scripting (XSS) vulnerability exists in `@angular/platform-server`'s DOM emulation dependency (`domino`) when serializing the content of `<noscript>` elements. When rendering dynamic text content inside a `<noscript>` element via template bindings (such as `{{ value }}` or `[textContent]`), the template engine expects the browser to render the content safely. Under Server-Side Rendering (SSR), `domino` is configured with scripting enabled, meaning `<noscript>` is treated as a raw-text element. However, `domino`'s serializer completely omitted `<noscript>` from the list of raw-text elements requiring closing-tag escaping during DOM serialization. As a result, any occurrence of `</noscript>` in the bound dynamic text was **never escaped under any circumstances**. The unescaped closing tag was serialized directly into the output HTML (e.g. `<noscript></noscript><script>alert(1)</script></noscript>`). When parsed by a browser, it closes the `<noscript>` block early, allowing the injected `<script>` block to execute in the user's browser context, causing same-origin Cross-Site Scripting (XSS). ### Impact This vulnerability allows an attacker to perform same-origin Cross-Site Scripting (XSS) attacks against any user visiting an SSR-rendered page that binds user-controlled data inside a `<noscript>` element. This can lead to session hijacking, credentials theft, unauthorized actions on behalf of users, and defacement. ### Patched Versions - 22.0.0-rc.2 - 21.2.16


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Architectural layers (MAESTRO):