Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to 22.0.1, 21.2.17, and 20.3.25, to optimize client-side bootstrap in Server-Side Rendered (SSR) environments, Angular supports Hydration via provideClientHydration(). During SSR, Angular serializes the application's runtime state (such as cached HttpClient responses) and outputs it into the HTML stream as a <script> tag with a predictable identifier. During client bootstrap, Angular recovers this state by looking up the element via document.getElementById('ng-state') and parsing its text content. Because the DOM element lookup for the state container is predictable and relies solely on the ID selector (ng-state), it is susceptible to DOM Clobbering. If the application binds untrusted user input or CMS content to element properties such as id (e.g., <div [id]="userInput"> or <a id="ng-state">) before the genuine <script> tag is parsed by the browser, the attacker-controlled element takes precedence in the DOM lookup. During hydration, when Angular calls document.getElementById('ng-state'), the browser returns the attacker's clobbered element. Angular then attempts to parse the text content or attributes of this clobbered element as JSON. This vulnerability is fixed in 22.0.1, 21.2.17, and 20.3.25.

Affected: npm: @angular/core

To optimize client-side bootstrap in Server-Side Rendered (SSR) environments, Angular supports **Hydration** via `provideClientHydration()`. During SSR, Angular serializes the application's runtime state (such as cached `HttpClient` responses) and outputs it into the HTML stream as a `<script>` tag with a predictable identifier:

```html <script type="application/json" id="ng-state"> {"some-api-url": {"body": ...}} </script> ````

During client bootstrap, Angular recovers this state by looking up the element via `document.getElementById('ng-state')` and parsing its text content.

Because the DOM element lookup for the state container is predictable and relies solely on the ID selector (`ng-state`), it is susceptible to **DOM Clobbering**.

If the application binds untrusted user input or CMS content to element properties such as `id` (e.g., `<div [id]="userInput">` or `<a id="ng-state">`) *before* the genuine `<script>` tag is parsed by the browser, the attacker-controlled element takes precedence in the DOM lookup.

During hydration, when Angular calls `document.getElementById('ng-state')`, the browser returns the attacker's clobbered element. Angular then attempts to parse the text content or attributes of this clobbered element as JSON.

### Impact

By clobbering the state element, the attacker can inject a custom JSON payload into Angular's `TransferState` cache. The most critical exploitation vector is poisoning the **HTTP Transfer Cache**.

1. The attacker injects…

Affected: Ubuntu:Pro:16.04:LTS: angular.js, Ubuntu:Pro:18.04:LTS: angular.js, Ubuntu:Pro:20.04:LTS: angular.js, Ubuntu:22.04:LTS: angular.js, Ubuntu:24.04:LTS: angular.js, Ubuntu:25.10: angular.js, Ubuntu:26.04:LTS: angular.js

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Prior to 22.0.1, 21.2.17, and 20.3.25, to optimize client-side bootstrap in Server-Side Rendered (SSR) environments, Angular supports Hydration via provideClientHydration(). During SSR, Angular serializes the application's runtime state (such as cached HttpClient responses) and outputs it into the HTML stream as a <script> tag with a predictable identifier. During client bootstrap, Angular recovers this state by looking up the element via document.getElementById('ng-state') and parsing its text content. Because the DOM element lookup for the state container is predictable and relies solely on the ID selector (ng-state), it is susceptible to DOM Clobbering. If the application binds untrusted user input or CMS content to element properties such as id (e.g., <div [id]="userInput"> or <a id="ng-state">) before the genuine <script> tag is parsed by the browser, the attacker-controlled element takes precedence in the DOM lookup. During hydration, when Angular calls document.getElementById('ng-state'), the browser returns the attacker's clobbered element. Angular then attempts to parse the text content or attributes of this clobbered element as JSON. This vulnerability is fixed in 22.0.1, 21.2.17, and 20.3.25.

Ein Angreifer kann mehrere Schwachstellen in Angular ausnutzen, um erweiterte Berechtigungen zu erlangen, beliebigen Code auszuführen, Sicherheitsmaßnahmen zu umgehen, Cross-Site-Scripting-Angriffe durchzuführen, einen Denial-of-Service-Zustand herbeizuführen, Daten zu manipulieren oder offenzulegen, Benutzer auf bösartige Websites umzuleiten oder Sitzungen zu kapern.