CVE-2025-71401 better-auth before 1.4.2 basePath Modification DoS
An attacker can cause a denial of service by poisoning the base path if the URL is not explicitly configured, affecting better-auth users.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-71401?
CVE-2025-71401 is a critical denial of service vulnerability in better-auth, published on 2 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
better-auth (npm) before 1.4.2 allows an external request to configure baseURL when it is not otherwise defined (e.g., BETTER_AUTH_URL is unset). An attacker able to make the very first request to the server after startup can poison the router's base path, causing all routes to return 404 for all users (denial of service). The issue is not reachable when baseURL is explicitly configured or on typical managed hosting platforms.
Weakness: CWE-770
Which versions are affected by CVE-2025-71401?
2 open source packages ship an affected version, including better-auth.
| Package | Affected | Fixed in |
|---|---|---|
better-auth npm | All versions | 1.4.2 |
better-auth npm | All versions | 1.4.2 |
How do I fix CVE-2025-71401?
Upgrade better-auth to 1.4.2 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-71401 being exploited?
There is no known exploitation of CVE-2025-71401 in the wild and no public exploit code.
Sources
Also known as GHSA-569q-mpph-wgww.