CVE-2026-27739

CRITICAL

Angular CLI <21.2.0-rc.1, 21.0.0-21.1.4, 20.0.0-20.3.16, <19.2.21 - SSRF via Unvalidated Headers

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 4 public exploits for CVE-2026-27739. PoCs published by XiaomingX, adminlove520, mr-redoo7.

AI-analyzed exploit summary This repository contains a functional Python exploit for CVE-2026-27739, targeting Angular Universal SSR applications with SSRF and header injection vulnerabilities. The exploit demonstrates SSRF via unsanitized headers and prototype pollution, with automated testing for AWS/GCP metadata endpoints and local services.

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.

Exploits (4)

github WORKING POC 10 stars
by XiaomingX · pythonpoc
https://github.com/XiaomingX/data-cve-poc-py-v1/tree/main/2026/CVE-2026-27739

This repository contains a functional Python exploit for CVE-2026-27739, targeting Angular Universal SSR applications with SSRF and header injection vulnerabilities. The exploit demonstrates SSRF via unsanitized headers and prototype pollution, with automated testing for AWS/GCP metadata endpoints and local services.

Classification
Working Poc 95%
Attack Type
Ssrf
Complexity
Moderate
Reliability
Reliable
Target: Angular Universal SSR applications
No auth needed
Prerequisites: Network access to the target Angular SSR application · Target application must process unsanitized headers
devstral-2 · analyzed Mar 12, 2026 Full analysis →
github WORKING POC 3 stars
by adminlove520 · pythonpoc
https://github.com/adminlove520/CVE-Poc_All_in_One/tree/main/2026/CVE-2026-27739

This repository contains a functional Python exploit for CVE-2026-27739, targeting Angular Universal SSR applications with SSRF and header injection vulnerabilities. The exploit demonstrates SSRF via unsanitized headers and attempts to extract sensitive data from cloud metadata services.

Classification
Working Poc 95%
Attack Type
Ssrf
Complexity
Moderate
Reliability
Reliable
Target: Angular Universal SSR applications
No auth needed
Prerequisites: Network access to the target Angular SSR application · Target application must process unsanitized headers
devstral-2 · analyzed May 04, 2026 Full analysis →
nomisec WORKING POC
by mr-redoo7 · poc
https://github.com/mr-redoo7/CVE-2026-27739-POC

This repository contains a functional Python exploit for CVE-2026-27739, targeting Angular Universal SSR applications with SSRF and header injection vulnerabilities. The PoC demonstrates SSRF via unsanitized headers and prototype pollution, with automated testing for AWS/GCP metadata endpoints and local services.

Classification
Working Poc 95%
Attack Type
Ssrf
Complexity
Moderate
Reliability
Reliable
Target: Angular Universal SSR applications
No auth needed
Prerequisites: Network access to the target Angular SSR application · Target application must process unsanitized headers
devstral-2 · analyzed Apr 09, 2026 Full analysis →
nomisec WORKING POC
by bankerke · poc
https://github.com/bankerke/-CVE-2026-27739-poc

This repository contains a functional Python exploit for CVE-2026-27739, targeting Angular Universal SSR applications vulnerable to SSRF and header injection via unsanitized X-Forwarded-* headers. The PoC demonstrates SSRF to internal services (AWS IMDS, GCP metadata) and header manipulation through prototype pollution.

Classification
Working Poc 95%
Attack Type
Ssrf
Complexity
Moderate
Reliability
Reliable
Target: Angular Universal SSR (version not specified)
No auth needed
Prerequisites: Network access to target Angular SSR application · Target application must process X-Forwarded-* headers unsafely
devstral-2 · analyzed Mar 11, 2026 Full analysis →

Scores

CVSS v4 9.2
EPSS 0.0050
EPSS Percentile 38.5%
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-918
Status published
Products (6)
angular/@nguniversal/common <= 16.2.0
angular/@nguniversal/express-engine <= 16.2.0
angular/angular-cli < 19.2.21
angular/angular-cli >= 20.0.0-next.0, < 20.3.17
angular/angular-cli >= 21.0.0-next.0, < 21.1.5
angular/angular-cli >= 21.2.0-next.2, < 21.2.0-rc.0
Published Feb 25, 2026
Tracked Since Feb 26, 2026