Mitigation Strategies

To mitigate this vulnerability immediately, you should upgrade Angular to one of the patched versions: 22.0.1, 21.2.17, or 20.3.25, where the weak hash algorithm has been replaced with a cryptographically secure SHA-256 implementation.

If upgrading is not immediately possible, temporary mitigations include disabling transfer caching for sensitive endpoints or disabling transfer caching globally via configuration.

These steps prevent attackers from exploiting hash collisions to poison the TransferState cache during SSR.

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Compliance Impact

The vulnerability in Angular's HttpTransferCache allows attackers to cause state poisoning by overwriting cached responses with attacker-controlled data. This can lead to the application running with forged data, potentially bypassing security controls or enabling DOM-based XSS, and may result in information leakage if sensitive data is rendered on the page.

Such unauthorized data manipulation and potential exposure of sensitive information could negatively impact compliance with common standards and regulations like GDPR and HIPAA, which require protection of personal and sensitive data against unauthorized access and integrity violations.

Mitigations include updating Angular to patched versions that use a cryptographically secure SHA-256 hashing algorithm for cache keys or disabling transfer caching for sensitive endpoints, helping to maintain compliance by preventing data tampering and leakage.

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Executive Summary

This vulnerability exists in Angular's HttpTransferCache, which caches HTTP requests during Server-Side Rendering (SSR) to reuse them during client-side hydration. The cache keys are generated using a weak 32-bit DJB2-like polynomial rolling hash, which has a very small hash space.

Attackers can exploit this by finding query parameter strings that produce the same 32-bit hash as sensitive endpoints. When a victim visits a crafted link with such a parameter, the SSR executes both the attacker-controlled and sensitive requests, causing the attacker-controlled response to overwrite the legitimate one in the cache.

This leads to state poisoning, where the application runs with forged data, potentially bypassing security controls, enabling DOM-based cross-site scripting (XSS), or causing information leakage if sensitive data is rendered on the page.

The vulnerability affects Angular versions from 19.2.25 up to 22.0.0-next.0 and is fixed in versions 22.0.1, 21.2.17, and 20.3.25 by replacing the weak hash with a cryptographically secure SHA-256 algorithm.

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Impact Analysis

This vulnerability can impact you by allowing attackers to poison the server-side rendered cache with forged data. This can cause your application to run with incorrect or malicious data.

Such state poisoning can lead to security control bypasses, DOM-based cross-site scripting (XSS) attacks, and leakage of sensitive information if the forged data includes confidential responses.

Because exploitation requires no privileges or user interaction, it poses a high risk to applications using vulnerable Angular versions.

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Detection Guidance

Detection of this vulnerability involves identifying if your Angular application is using vulnerable versions of HttpTransferCache that employ the weak 32-bit DJB2-like polynomial rolling hash for caching HTTP requests during Server-Side Rendering (SSR).

You can check the Angular version used in your project to see if it is prior to the patched versions 22.0.1, 21.2.17, or 20.3.25.

Commands to detect the Angular version in your project include:

• Run `ng version` in your project directory to display the Angular CLI and framework versions.
• Check the package.json file for the Angular dependencies and their versions using `cat package.json | grep '@angular/core'`.

Additionally, monitoring HTTP requests during SSR for unusual cache key collisions or unexpected overwrites in TransferState could indicate exploitation attempts, but no specific commands for this detection are provided.

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