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.
Published: 2026-08-02
Score: 9.3 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Tue, 04 Aug 2026 09:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 03 Aug 2026 11:30:00 +0000

Type Values Removed Values Added
Title better-auth before 1.4.1 basePath Modification DoS better-auth before 1.4.2 basePath Modification DoS

Sun, 02 Aug 2026 16:45:00 +0000

Type Values Removed Values Added
First Time appeared Better-auth better Auth
Vendors & Products Better-auth better Auth

Sun, 02 Aug 2026 12:45:00 +0000

Type Values Removed Values Added
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.
Title better-auth before 1.4.1 basePath Modification DoS
First Time appeared Better-auth
Better-auth better-auth\/oauth-provider
Weaknesses CWE-770
CPEs cpe:2.3:a:better-auth:better-auth\/oauth-provider:*:*:*:*:*:node.js:*:*
Vendors & Products Better-auth
Better-auth better-auth\/oauth-provider
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}


Subscriptions

Better-auth Better-auth\/oauth-provider Better Auth
cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-08-03T14:29:35.454Z

Reserved: 2026-07-18T12:38:41.077Z

Link: CVE-2025-71401

cve-icon Vulnrichment

Updated: 2026-08-03T14:29:32.189Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-03T09:30:17Z

Weaknesses