CVE-2026-27739Angular SSR is vulnerable to SSRF and Header Injection via request handling pipeline

Description

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.

Timeline

Scores

EPSS (exploitation in 30 days)

0.55% · top 53% of all CVEs (13 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: yes · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.2.

Affected products

• angular · angular-cli

  • affected >= 21.2.0-next.2, < 21.2.0-rc.0
  • affected >= 21.0.0-next.0, < 21.1.5
  • affected >= 20.0.0-next.0, < 20.3.17
  • affected < 19.2.21

• angular · @nguniversal/common

  • affected <= 16.2.0

• angular · @nguniversal/express-engine

  • affected <= 16.2.0

Affected packages

From reviewed advisories of the GitHub Advisory Database.

• npm@angular/ssrGHSA-x288-3778-4hhx (opens in a new tab)
• npm@nguniversal/commonGHSA-x288-3778-4hhx (opens in a new tab)
• npm@nguniversal/express-engineGHSA-x288-3778-4hhx (opens in a new tab)

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-8695 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisory GHSA-x288-3778-4hhx (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-27739](https://cveledger.app/badge/CVE-2026-27739.svg)](https://cveledger.app/cve/CVE-2026-27739)

Record last updated 27 Feb 2026, 17:59 UTC.