---
cve: "CVE-2026-73420"
severity: "CRITICAL"
cvss: 9.1
epss: "0.5%"
vendor: "nextauthjs"
kev: false
exploited: false
published: "2026-08-13 22:17:26"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-21T10:13:22+02:00"
---

# CVE-2026-73420

> 9.1 CRITICAL · 🧪 PoC

## Beschreibung

NextAuth.js provides authentication for Next.js. Prior to @auth/core 0.41.3 and next-auth 4.24.15 and 5.0.0-beta.32, the defaultNormalizer used by the email and magic-link sign-in flow validates an address before applying Unicode normalization. An address can contain a Unicode character such as U+FF20 FULLWIDTH COMMERCIAL AT that is not ASCII at-sign but canonicalizes to an ASCII at-sign under NFKC or NFKD normalization. The address passes the normalizer's single-at-sign check, but a downstream sendVerificationRequest mail library or delivery service that normalizes the address can then see two at-sign separators and deliver the passwordless sign-in link to an attacker-controlled recipient. Applications are affected when the email provider uses the built-in normalizer rather than a custom normalizeIdentifier and the downstream sender applies Unicode normalization. An attacker who knows a victim's email address can request the misrouted magic link and sign in as the victim without victim interaction. This issue is fixed in @auth/core 0.41.3 and next-auth 4.24.15 and 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)

- d857eec560fb99c8b18d3b22a2693b849a62d1c3 (Commit)
- e293b3746616660f0844347a68d09eac54b95c6f (Commit)

## Referenzen

- <https://github.com/nextauthjs/next-auth/security/advisories/GHSA-7rqj-j65f-68wh>
- <https://github.com/nextauthjs/next-auth/commit/19d2feb24359fa8c79418907fc68d9ec8152ca94>
- <https://github.com/nextauthjs/next-auth/commit/a63eee12a1a20cb35209e44195b097868517b9a0>
- <https://github.com/nextauthjs/next-auth/releases/tag/@auth/core@0.41.3>
- <https://github.com/nextauthjs/next-auth/releases/tag/next-auth@4.24.15>
- <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-2026-73420) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_