---
cve: "CVE-2026-73421"
severity: "CRITICAL"
cvss: 9.1
epss: "46%"
vendor: "nextauthjs"
kev: false
exploited: false
published: "2026-08-13 22:17:26"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-19T03:44:22+02:00"
---

# CVE-2026-73421

> 9.1 CRITICAL · 🧪 PoC

## Beschreibung

NextAuth.js provides authentication for Next.js. From next-auth 5.0.0-beta.0 until 5.0.0-beta.32, applications that gate access by checking only for the existence of the auth object returned by the auth() wrapper can fail open when Auth.js has a server configuration error. In middleware, Route Handlers, React Server Components, and other auth() entry points, a non-OK session response is parsed into a truthy error object instead of null, so checks such as !!auth and if (req.auth) evaluate to true for unauthenticated requests. A provider missing both the issuer and authorization endpoint triggers InvalidEndpoints, and an unset AUTH_SECRET or another server configuration error can produce the same behavior. There is no impact while configuration is valid, but after a deployment becomes misconfigured, routes protected only by session existence silently grant access to every visitor. This issue is fixed in next-auth 5.0.0-beta.32.

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- d008b9b764bf4b322a87e1822d1dda7789258d8f (Commit)
- e293b3746616660f0844347a68d09eac54b95c6f (Commit)

## Referenzen

- <https://github.com/nextauthjs/next-auth/security/advisories/GHSA-8fpg-xm3f-6cx3>
- <https://github.com/nextauthjs/next-auth/commit/d008b9b764bf4b322a87e1822d1dda7789258d8f>
- <https://github.com/nextauthjs/next-auth/releases/tag/next-auth@5.0.0-beta.32>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-73421) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_