CVE-2026-27739
NoneCVSS
—
EPSS
0.5%
Published
Feb 25, 2026
CISA due date
—
The record
The Angular SSR is a server-rise rendering tool for Angular applications. Versions prior to 21.2.0-rc.1, 21.1.5, 20.3.17, and 19.2.21 have a Server-Side Request Forgery (SSRF) vulnerability 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 host domain, path and character sanitization, and port validation. This vulnerability manifests in two primary ways: implicit relative URL resolution and explicit manual construction. When successfully exploited, this vulnerability allows for arbitrary internal request steering. This can lead to credential exfiltration, internal network probing, and a confidentiality breach. In order to be vulnerable, the 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, the application server must be reachable by an attacker who can influence these headers without strict validation from a front-facing proxy, and the infrastructure (Cloud, CDN, or Load Balancer) must not sanitize or validate incoming headers. Versions 21.2.0-rc.1, 21.1.5, 20.3.17, and 19.2.21 contain a patch. Some workarounds are available. Avoid using `req.headers` for URL construction. Instead, use trusted variables for base API paths. Those who cannot upgrade immediately should implement a middleware in their `server.ts` to enforce numeric ports and validated hostnames.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| npm | @angular/ssr | 0 | 19.2.21 |
| npm | @angular/ssr | 20.0.0-next.0 | 20.3.17 |
| npm | @angular/ssr | 21.0.0-next.0 | 21.1.5 |
| npm | @angular/ssr | 21.2.0-next.0 | 21.2.0-rc.1 |
| npm | @nguniversal/common | 0 | No fix |
| npm | @nguniversal/express-engine | 0 | No fix |
Related vulnerabilities
- GHSA-x288-3778-4hhx Angular SSR is vulnerable to SSRF and Header Injection via request handling pipeline Same vulnerability
- CVE-2026-44437 The Angular SSR is a server-rise rendering tool for Angular applications. Also affects @angular/ssr
- GHSA-69xr-m8h6-h664 Angular SSR has Open Redirect and Request Steering via Encoded X-Forwarded-Prefix Also affects @angular/ssr
- CVE-2026-33397 The Angular SSR is a server-rise rendering tool for Angular applications. Also affects @angular/ssr
- GHSA-vfx2-hv2g-xj5f Protocol-Relative URL Injection via Single Backslash Bypass in Angular SSR Also affects @angular/ssr
- GHSA-xh43-g2fq-wjrj Angular SSR has an Open Redirect via X-Forwarded-Prefix Also affects @angular/ssr
- CVE-2026-27738 The Angular SSR is a server-rise rendering tool for Angular applications. Also affects @angular/ssr
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