CVE-2026-45364 (GCVE-0-2026-45364)
Vulnerability from cvelistv5
Published
2026-05-28 21:34
Modified
2026-05-29 19:05
Severity ?
7.3 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
CWE
  • CWE-307 - Improper Restriction of Excessive Authentication Attempts
Summary
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.
References
Impacted products
Vendor Product Version
better-auth better-auth Version: < 1.4.17
Version: >= 1.5.0-beta.1, < 1.5.0-beta.9
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