# CVE-2025-71399: Better Auth path normalization bypass of disabledPaths and rate limits

Source: https://junglewise.ai/threats/cve-2025-71399-better-auth-path-normalization-bypass-of-disabledpaths-and-rate  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-02. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2025-71399 · Severity: high · CVSS 8.6 · Published 2026-08-02

Better Auth is a comprehensive authentication framework used to manage user login and identity flows. An issue in its underlying router allows attackers to bypass security controls by using double-slash URLs (e.g., //sign-in/email instead of /sign-in/email), potentially circumventing disabled path restrictions and rate-limiting protections that are meant to prevent abuse.

Technologies: [better-auth (npm)](https://junglewise.ai/threats/technologies/better-auth). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2025-71399 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-71399 being exploited in the wild.

**How severe is CVE-2025-71399?** High severity, with a CVSS score of 8.6, published 2 August 2026.

**Which products and versions are affected?** better-auth (npm) SEMVER:introduced=0,fixed=1.4.5.

**Is there a fix for CVE-2025-71399?** Yes. better-auth (npm): upgrade to 1.4.5 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2025-71399 attacked?** It is attacked over the network.

**Am I affected by CVE-2025-71399?** Check whether you run better-auth (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- better-auth (npm): upgrade to 1.4.5 or later

  ```sh
  npm install better-auth@1.4.5
  ```


## Technical details

The vulnerability exists in the rou3 router library, which Better Auth uses via the better-call dependency. The affected versions of rou3 normalize URL paths by removing empty segments, causing /path, //path, and ///path to resolve to identical routes. If the network infrastructure does not normalize multiple slashes before reaching Better Auth (e.g., in environments without Vercel/Next.js or Cloudflare URL normalization enabled), an attacker can craft requests with double-slash paths to bypass path-based disabledPaths configuration and rate-limiting controls. The attack requires no authentication and can be exploited remotely over the network. The fix was introduced in rou3 after version 0.5.1; Better Auth v1.4.5 and later include the patched dependency.

## Affected products

- Better Auth Better Auth < 1.4.5

## Identifiers

- CVE-2025-71399
- GHSA-x732-6j76-qmhm

## Timeline

- 2025-12-16: disclosed
- 2025-12-16: patched: Better Auth v1.4.5 or later includes patched rou3

## References

- [https://github.com/better-auth/better-auth/security/advisories/GHSA-x732-6j76-qmhm](https://github.com/better-auth/better-auth/security/advisories/GHSA-x732-6j76-qmhm)
- [https://github.com/better-auth/better-auth](https://github.com/better-auth/better-auth)

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