Is CVE-2026-27738 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-27738 being exploited in the wild.

How severe is CVE-2026-27738?

Medium severity, with a CVSS score of 4, published 25 February 2026.

Which products and versions are affected?

@angular/ssr (npm) SEMVER:introduced=21.2.0-next.0,fixed=21.2.0-rc.1.

Is there a fix for CVE-2026-27738?

Yes. @angular/ssr (npm): upgrade to 21.2.0-rc.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-27738 attacked?

It is attacked over the network.

Am I affected by CVE-2026-27738?

Check whether you run @angular/ssr (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-27738: Angular SSR open redirect via X-Forwarded-Prefix header

CVE-2026-27738 · Severity: medium · CVSS 4 · Published 2026-02-25

Angular's server-side rendering (SSR) module is used to pre-render web applications on the server before sending them to browsers. An attacker can exploit incomplete URL validation in this module to trick users into visiting malicious websites. When the application is deployed behind a proxy that forwards the X-Forwarded-Prefix header, an attacker can inject a specially crafted header value that causes users to be redirected to an attacker-controlled domain, enabling phishing attacks and search engine poisoning.

Technologies: @angular/ssr (npm). Vendors: npm.

Quick answers

Is CVE-2026-27738 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-27738 being exploited in the wild.
How severe is CVE-2026-27738?: Medium severity, with a CVSS score of 4, published 25 February 2026.
Which products and versions are affected?: @angular/ssr (npm) SEMVER:introduced=21.2.0-next.0,fixed=21.2.0-rc.1.
Is there a fix for CVE-2026-27738?: Yes. @angular/ssr (npm): upgrade to 21.2.0-rc.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-27738 attacked?: It is attacked over the network.
Am I affected by CVE-2026-27738?: Check whether you run @angular/ssr (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

@angular/ssr (npm): upgrade to 21.2.0-rc.1 or later
```
npm install @angular/ssr@21.2.0-rc.1
```

Technical details

The vulnerability exists in Angular SSR's URL processing logic, which normalizes URL segments by stripping leading slashes but only removes a single slash. When an attacker provides an X-Forwarded-Prefix header value starting with three slashes (e.g., ///evil.com), Angular strips one slash, leaving //evil.com. This double-slash prefix is interpreted by modern browsers as a protocol-relative URL, causing redirects to attacker-controlled domains. The attack requires the application to use Angular SSR with routes that perform internal redirects, a proxy that passes X-Forwarded-Prefix without sanitization, and caching that doesn't vary on this header. Patches are available in versions 21.2.0-rc.1, 21.1.5, 20.3.17, and 19.2.21; a workaround involves sanitizing the header in server.ts before Angular processes the request.

Affected products

Google Angular SSR 19.0.0-next.0 through 19.2.20, 20.0.0-next.0 through 20.3.16, 21.0.0-next.0 through 21.1.4, 21.2.0-next.0 through 21.2.0-rc.0

Identifiers

CVE-2026-27738
GHSA-xh43-g2fq-wjrj

Timeline

2026-02-25: disclosed
2026-02-25: patched: Patches released: 19.2.21, 20.3.17, 21.1.5, 21.2.0-rc.1

References

https://github.com/angular/angular-cli/security/advisories/GHSA-xh43-g2fq-wjrj

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