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CVE-2026-27738 Detail

Description

The Angular SSR is a server-rise rendering tool for Angular applications. An Open Redirect vulnerability exists in the internal URL processing logic in versions on the 19.x branch prior to 19.2.21, the 20.x branch prior to 20.3.17, and the 21.x branch prior to 21.1.5 and 21.2.0-rc.1. The logic normalizes URL segments by stripping leading slashes; however, it only removes a single leading slash. When an Angular SSR application is deployed behind a proxy that passes the `X-Forwarded-Prefix` header, an attacker can provide a value starting with three slashes. This vulnerability allows attackers to conduct large-scale phishing and SEO hijacking. In order to be vulnerable, the application must use Angular SSR, the application must have routes that perform internal redirects, the infrastructure (Reverse Proxy/CDN) must pass the `X-Forwarded-Prefix` header to the SSR process without sanitization, and the cache must not vary on the `X-Forwarded-Prefix` header. Versions 21.2.0-rc.1, 21.1.5, 20.3.17, and 19.2.21 contain a patch. Until the patch is applied, developers should sanitize the `X-Forwarded-Prefix` header in their`server.ts` before the Angular engine processes the request.


Metrics

NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

Nist CVSS score does not match with CNA score
CNA:  GitHub, Inc.
CVSS-B 6.9 MEDIUM
Vector:  CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://github.com/angular/angular-cli/commit/877f017ace4b83277d773aa37f5813e5e9faec7e GitHub, Inc.
https://github.com/angular/angular-cli/issues/32501 GitHub, Inc.
https://github.com/angular/angular-cli/pull/32521 GitHub, Inc.
https://github.com/angular/angular-cli/security/advisories/GHSA-xh43-g2fq-wjrj GitHub, Inc.

Weakness Enumeration

CWE-ID CWE Name Source
CWE-601 URL Redirection to Untrusted Site ('Open Redirect') GitHub, Inc.  

Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-27738
NVD Published Date:
02/25/2026
NVD Last Modified:
02/25/2026
Source:
GitHub, Inc.