GHSA-x288-3778-4hhx: Angular SSR is vulnerable to SSRF and Header Injection via request handling pipeline
A [Server-Side Request Forgery (SSRF)](https://developer.mozilla.org/en-US/docs/Web/Security/Attacks/SSRF) vulnerability has been identified in the Angular SSR request handling pipeline. The vulnerability exists because Angular’s internal URL reconstruction logic directly trusts and consumes user-controlled HTTP headers specifically the Host and `X-Forwarded-*` family to determine the application's base origin without any validation of the destination domain.Specifically, the framework didn't have checks for the following:**Host Domain**: The `Host` and `X-Forwarded-Host` headers were not checked to belong to a trusted origin. This allows an attacker to redefine the "base" of the application to an arbitrary external domain.**Path & Character Sanitization**: The `X-Forwarded-Host` header was not checked for path segments or special characters, allowing manipulation of the base path for all resolved relative URLs.**Port Validation**: The `X-Forwarded-Port` header was not verified as numeric, leading to malformed URI construction or injection attacks.This vulnerability manifests in two primary ways:**Implicit Relative URL Resolution**: Angular's `HttpClient` resolves relative URLs against this unvalidated and potentially malformed base origin. An attacker can "steer" these requests to an external server or internal service.**Explicit Manual Construction**: Developers injecting the `REQUEST` object to manually construct URLs (for fetch or third-party SDKs) directly inherit these unsanitized values. By accessing the `Host` / `X-Forwarded-*` headers, the application logic may perform requests to attacker-controlled destinations or malformed endpoints.ImpactWhen successfully exploited, this vulnerability allows for arbitrary internal request steering. This can lead to:**Credential Exfiltration**: Stealing sensitive `Authorization` headers or session cookies by redirecting them to an attacker's server.**Internal Network Probing**: Accessing and transmitting data from internal services, databases, or cloud metadata endpoints (e.g., `169.254.169.254`) not exposed to the public internet.Confidentiality Breach: Accessing sensitive information processed within the application's server-side context.Attack PreconditionsThe victim application must use Angular SSR (Server-Side Rendering).The application must perform `HttpClient` requests using relative URLs OR manually construct URLs using the unvalidated `Host` / `X-Forwarded-*` headers using the `REQUEST` object.**Direct Header Access**: The application server is reachable by an attacker who can influence these headers without strict validation from a front-facing proxy.**Lack of Upstream Validation**: The infrastructure (Cloud, CDN, or Load Balancer) does not sanitize or validate incoming headers.Patches21.2.0-rc.121.1.520.3.1719.2.21Workarounds**Use Absolute URLs:** Avoid using `req.headers` for URL construction. Instead, use trusted variables for your base API paths.**Implement Strict Header Validation (Middleware)**: If you cannot upgrade immediately, implement a middleware in your `server.ts` to enforce numeric ports and validated hostnames.References[Fix](https://github.com/angular/angular-cli/pull/32516)[Docs](https://angular.dev/best-practices/security#preventing-server-side-request-forgery-ssrf)
CVSS v4.0: 9.2