Server-Side Rendering Vulnerability in Angular Applications

CVE-2026-27739

What is CVE-2026-27739?

CVE-2026-27739 is a significant vulnerability discovered in the Angular framework's Server-Side Rendering (SSR) feature, specifically affecting versions prior to 21.2.0-rc.1, 21.1.5, 20.3.17, and 19.2.21. Angular SSR is intended to enable developers to render Angular applications on the server, improving performance and SEO. However, this vulnerability introduces a Server-Side Request Forgery (SSRF) flaw in the request handling pipeline. The issue arises from Angular's internal URL reconstruction logic, which does not adequately validate user-controlled HTTP headers, such as the Host and X-Forwarded-* headers. This oversight can result in arbitrary internal request manipulation, allowing attackers to exploit the framework's request processing. The consequences could be dire for organizations relying on this technology, as it opens the door to credential theft, unauthorized network access, and breaches of sensitive data.

Potential impact of CVE-2026-27739

1. Credential Exfiltration: Attackers may exploit this vulnerability to retrieve sensitive authentication information from internal systems, potentially gaining access to critical resources and accounts.

2. Internal Network Probing: The SSRF vulnerability can enable attackers to probe internal networks, allowing them to discover and exploit additional vulnerabilities within the organization's infrastructure.

3. Confidentiality Breach: Successful exploitation of this flaw can lead to significant breaches of confidentiality, as unauthorized access may allow attackers to view or manipulate sensitive data housed within the affected systems.

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