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CVE-2026-41423 — Vulnerability in @angular/platform-server — CVE...

HIGH

Angular: SSRF via protocol-relative and backslash URLs in Angular Platform-Server

Published April 16, 2026Updated May 12, 2026Source: osv

Summary

### Impact A [Server-Side Request Forgery (SSRF)](https://developer.mozilla.org/en-US/docs/Web/Security/Attacks/SSRF) vulnerability exists in `@angular/platform-server` due to improper handling of URLs during Server-Side Rendering (SSR). When an attacker sends a request such as `GET /\evil.com/ HTTP/1.1` the server engine (Express, etc.) passes the URL string to Angular’s rendering functions. Because the URL parser normalizes the backslash to a forward slash for HTTP/HTTPS schemes, the internal state of the application is hijacked to believe the current origin is `evil.com`. This misinterpretation tricks the application into treating the attacker’s domain as the local origin. Consequently, any relative `HttpClient` requests or `PlatformLocation.hostname` references are redirected to the attacker controlled server, potentially exposing internal APIs or metadata services. **Affected APIs:** - `renderModule` - `renderApplication` - `CommonEngine` (from `@angular/ssr`) **Non-Affected APIs:** - `AngularAppEngine` (from `@angular/ssr`) - `AngularNodeAppEngine` (from `@angular/ssr`) ### Attack Preconditions - The server has outbound network access. - The application uses Angular SSR via the affected APIs. - A pathname is passed as URL to the rendering method (e.g. using `req.url`). - The server-side code performs HTTP requests using `HttpClient` with relative URLs or uses `PlatformLocation.hostname` to build URLs. ### Patches - 22.0.0-next.8 - 21.2.9 - 20.3.19 - 19.2.21 ### Workarounds Developers should implement a middleware to sanitize the request URL before it reaches Angular. This involves stripping or normalizing leading slashes: ```js app.use((req, res, next) => { // Sanitize the URL to ensure it starts with a single forward slash if (req.url.startsWith('//') || req.url.startsWith('/\\') || req.url.startsWith('\\')) { req.url = '/' + req.url.replace(/^[/\\]+/, ''); } next(); }); ``` ### References - [Fix](https://github.com/angular/angular/pull/68194)

Advisory Timeline

  • First published April 16, 2026 (178 days ago).
  • Last revised May 12, 2026 — 26 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

npm
Update @angular/platform-server to 22.0.0-next.8 or later
npm install @angular/platform-server@22.0.0-next.8
npm
Update @angular/platform-server to 21.2.9 or later
npm install @angular/platform-server@21.2.9
npm
Update @angular/platform-server to 19.2.21 or later
npm install @angular/platform-server@19.2.21
npm
Update @angular/platform-server to 20.3.19 or later
npm install @angular/platform-server@20.3.19

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (5)

Affects 1 ecosystem: npm (1).

PackageEcosystemAffectedFixed In
@angular/platform-server
npm
All versions22.0.0-next.8
@angular/platform-server
npm
All versions21.2.9
@angular/platform-server
npm
All versionsRange-based data available
@angular/platform-server
npm
All versions19.2.21
@angular/platform-server
npm
All versions20.3.19

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

  • CWE-918
    Server-Side Request Forgery (SSRF)MITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 8.6 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
—
Confidentiality
—
Integrity
—
Availability
—

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:L/SI:L/SA:N

Frequently Asked Questions

What is CVE-2026-41423?
Angular: SSRF via protocol-relative and backslash URLs in Angular Platform-Server This vulnerability has been assigned a severity rating of HIGH (CVSS score: 8.6/10).
How do I check if my project is affected by CVE-2026-41423?
CVE-2026-41423 affects @angular/platform-server. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-41423 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
8.6

High exploitability or significant impact. Prioritize remediation within days.

Also Known As

GHSA-45q2-gjvg-7973

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  • CVE-2026-50168
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