Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-33397— Angular SSR Vulnerable to Protocol-Relative URL Injection via Single Backslash Bypass

Quick assessment

Affected
angular angular-cli
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Angular是Angular开源的一个开发平台。用于使用 Typescript / JavaScript 和其他语言构建移动和桌面 Web 应用程序。 Angular SSR 22.0.0-next.2之前版本、21.2.3之前版本和20.3.21之前版本存在输入验证错误漏洞，该漏洞源于对X-Forwarded-Prefix标头验证不完整，可能导致开放重定向和Web缓存投毒。

AI Predicted 6.1 Difficulty: Moderate EPSS 0.33% · P24
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-33397

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
Angular SSR Vulnerable to Protocol-Relative URL Injection via Single Backslash Bypass
Source: CVE Program / CVE List V5
Vulnerability Description
The Angular SSR is a server-rise rendering tool for Angular applications. Versions on the 22.x branch prior to 22.0.0-next.2, the 21.x branch prior to 21.2.3, and the 20.x branch prior to 20.3.21 have an Open Redirect vulnerability in `@angular/ssr` due to an incomplete fix for CVE-2026-27738. While the original fix successfully blocked multiple leading slashes (e.g., `///`), the internal validation logic fails to account for a single backslash (`\`) bypass. When an Angular SSR application is deployed behind a proxy that passes the `X-Forwarded-Prefix` header, an attacker provides a value starting with a single backslash, the internal validation failed to flag the single backslash as invalid, the application prepends a leading forward slash, resulting in a `Location` header containing the URL, and modern browsers interpret the `/\` sequence as `//`, treating it as a protocol-relative URL and redirecting the user to the attacker-controlled domain. Furthermore, the response lacks the `Vary: X-Forwarded-Prefix` header, allowing the malicious redirect to be stored in intermediate caches (Web Cache Poisoning). Versions 22.0.0-next.2, 21.2.3, and 20.3.21 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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
指向未可信站点的URL重定向(开放重定向)
Source: CVE Program / CVE List V5
Vulnerability Title
Angular 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Angular是Angular开源的一个开发平台。用于使用 Typescript / JavaScript 和其他语言构建移动和桌面 Web 应用程序。 Angular SSR 22.0.0-next.2之前版本、21.2.3之前版本和20.3.21之前版本存在输入验证错误漏洞，该漏洞源于对X-Forwarded-Prefix标头验证不完整，可能导致开放重定向和Web缓存投毒。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
angular angular-cli >= 22.0.0-next.0, < 22.0.0-next.2 -

II. Public POCs for CVE-2026-33397

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-33397

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-33397 (1)

Vendor Advisories for CVE-2026-33397 (2)

IV. Related Vulnerabilities

Same product: angular-cli
Same vendor: angular
Same weakness: CWE-601

V. Comments for CVE-2026-33397

No comments yet

Leave a comment