---
id: CVE-2025-71399
title: 'Better Auth relies on better-call, which uses the rou3 router library'
summary: >-
  Better Auth relies on better-call, which uses the rou3 router library. In
  affected versions of rou3, paths are normalized by removing empty segments, so
  /path, //path, and ///path resolve to the same route. In Better Auth versions
  prior …
severity: high
cvss: 8.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H'
cwe:
  - CWE-20
vendor: better-auth
product: better-auth
affected:
  - better-auth < 1.4.5
published: '2026-08-02'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T16:16:53.243'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-71399'
references:
  - url: >-
      https://github.com/better-auth/better-auth/commit/f60b43fa648399534507c9ac7db36d705b8874c3
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/better-auth/better-auth/security/advisories/GHSA-x732-6j76-qmhm
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/better-auth-before-path-normalization-bypass-via-rou3
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-08-03T15:48:08.348859Z'
epss: 0.0052
epssPercentile: 0.44291
ingestedAt: '2026-08-02T13:18:29.861Z'
---

## Overview

Better Auth relies on better-call, which uses the rou3 router library. In affected versions of rou3, paths are normalized by removing empty segments, so /path, //path, and ///path resolve to the same route. In Better Auth versions prior to 1.4.5 (which bundles the fixed rou3), this can allow attackers to bypass disabledPaths configuration and path-based rate limits by submitting requests with extra slashes in the URL path. The issue does not apply in deployments where the proxy or platform normalizes URLs by collapsing multiple slashes.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.