---
cve: "CVE-2026-33397"
severity: "MEDIUM"
cvss: 6.9
epss: "26%"
vendor: "angular"
kev: false
exploited: false
published: "2026-03-26 15:16:38"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-17T22:13:55+02:00"
---

# CVE-2026-33397

> 6.9 MEDIUM · 🧪 PoC

## Beschreibung

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.

## CVSS-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 34d524549b68912f8ebe4e656a342b797161d232 (Commit)
- ec8a04b9513cbabf7412ac20b7fdbab2e9faa166 (Commit)

## Referenzen

- <https://github.com/angular/angular-cli/security/advisories/GHSA-vfx2-hv2g-xj5f>
- <https://github.com/angular/angular-cli/pull/32771>
- <https://github.com/advisories/GHSA-xh43-g2fq-wjrj>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-33397) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_