@angular/common: Denial of Service (DoS) via OOM in Number Formatting (digitsInfo)

A Denial of Service (DoS) vulnerability exists in the `@angular/common` package of Angular. The `formatNumber` function, which is also utilized by `DecimalPipe`, `PercentPipe`, and `CurrencyPipe`, does not properly validate the upper bounds of the `digitsInfo` parameter. Specifically, the minimum and maximum fraction digits parsed from the `digitsInfo` string (e.g., `1.2-4`) are converted to integers and used without limits. When parsing a maliciously crafted `digitsInfo` string with excessively large fraction digit values (e.g., `1.200000000-200000000`), the internal `roundNumber` function attempts to pad the digits array to match the requested fraction size. This results in an unbounded loop that repeatedly pushes elements into an array. ### Impact Successful exploitation of this vulnerability allows an attacker to trigger resource exhaustion, leading to a Denial of Service (DoS): * **Server-Side Rendering (SSR):** In applications using SSR (e.g., `@angular/ssr`), an attacker can crash the Node.js server process due to a `JavaScript heap out of memory` error. This affects the availability of the application for all users. * **Client-Side Rendering (CSR):** In standard client-side applications, the unbounded loop will block the main thread, freezing the user's browser tab and making it unresponsive. ### Attack Preconditions For this vulnerability to be exploitable, the following conditions must be met: 1. **Vulnerable Component Usage:** The application must use Angular's number formatting utilities, such as the `formatNumber` function directly, or via template pipes (`DecimalPipe`, `PercentPipe`, `CurrencyPipe`). 2. **Attacker-Controlled Parameter:** The `digitsInfo` parameter passed to these utilities must be customizable or directly controlled by untrusted user input (e.g., parsed from query parameters, user preference settings, or API responses that accept user-defined formatting options). If `digitsInfo` is trusted or limited to a known, defined range for its value, the vulnerability is not exploitable by external attackers. ### Patches - 22.0.0-rc.2 - 21.2.15 - 20.3.22 - 19.2.23 ### References - https://github.com/angular/angular/pull/68840 ### Credits This vulnerability was discovered and reported by [CodeMender from Google DeepMind](https://deepmind.google/blog/introducing-codemender-an-ai-agent-for-code-security/).

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