---
cve: "CVE-2026-45364"
severity: "HIGH"
cvss: 7.3
epss: "0.3%"
vendor: "better-auth"
kev: false
exploited: false
published: "2026-05-28 22:17:00"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-23T01:26:06+02:00"
---

# CVE-2026-45364

> 7.3 HIGH · 🧪 PoC

## Beschreibung

Better Auth is an authentication and authorization library for TypeScript. Prior to 1.4.17 and 1.5.0-beta.9, Better Auth's HTTP rate limiter keyed each request by the exact textual IP address it received in x-forwarded-for (or the configured IP-bearing header). IPv6 clients controlling a typical /64 allocation could rotate through 2^64 distinct source addresses without exhausting the per-address counter, defeating rate limiting on /sign-in/email, /sign-up/email, /forget-password, and every other path the limiter protects. The same bug allowed a single client to vary the textual encoding of one IPv6 address (uppercase, compression, IPv4-mapped, hex-encoded IPv4-in-IPv6) and produce multiple distinct keys. This vulnerability is fixed in 1.4.17 and 1.5.0-beta.9.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Gering | warn |
| I Integrität | Gering | warn |
| A Verfügbarkeit | Gering | warn |

## Patch verfügbar (OSV)

- bcbeeee23c138fbcb01e972b945bb2e5846dcc0a (Commit)
- 6295dfcd349e0d10a08c251a10d2b3cd7568ebaf (Commit)

## Referenzen

- <https://github.com/better-auth/better-auth/security/advisories/GHSA-p6v2-xcpg-h6xw>
- <https://github.com/better-auth/better-auth/pull/7470>
- <https://github.com/better-auth/better-auth/pull/7509>
- <https://github.com/better-auth/better-auth/commit/43e719bcc0c223c7079fa0c611a9cf7ea1188254>
- <https://github.com/better-auth/better-auth/commit/57af0f7b910dcf7b1a5c0615d10b9bd56bb69bef>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-45364) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_