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CVE-2025-71399— Better Auth before 1.4.5 Path Normalization Bypass via rou3

Quick assessment

Affected
better-auth better-auth
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

better-auth是better-auth团队开源的一个身份验证框架。 better-auth 1.4.5之前版本存在输入验证错误漏洞，该漏洞源于路径规范化处理不当，可能导致攻击者通过提交带有额外斜杠的URL路径绕过禁用路径配置和基于路径的速率限制。

CVSS 8.6 · High EPSS 0.52% · P42

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProduct Version RangeStatus
better-auth better-auth < 1.4.5 affected
1.4.5 unaffected
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I. Basic Information for CVE-2025-71399

Vulnerability Information
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Vulnerability Title
Better Auth before 1.4.5 Path Normalization Bypass via rou3
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
better-auth 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
better-auth是better-auth团队开源的一个身份验证框架。 better-auth 1.4.5之前版本存在输入验证错误漏洞，该漏洞源于路径规范化处理不当，可能导致攻击者通过提交带有额外斜杠的URL路径绕过禁用路径配置和基于路径的速率限制。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
better-auth better-auth 0 ~ 1.4.5 -

II. Public POCs for CVE-2025-71399

# POC Description Source Link Shenlong Link
AI-Generated POC Verified env Premium
Reproduced successfully in a real sandbox · Below is the actual recording of building the environment and exploiting the vulnerability.
Reproduction recording is a Pro+ exclusive
Watch the full sandbox build + live exploit recording for this CVE. Limited-time ¥499/mo.
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claude_code · 7848 chars
GitHub 复现环境（可 clone 直接跑）
Pro+ exclusive includes:
Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
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POC zip download
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III. Intelligence Information for CVE-2025-71399

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Patches & Fixes for CVE-2025-71399 (1)

Vendor Advisories for CVE-2025-71399 (2)

Same Patch Batch · better-auth · 2026-08-02 · 3 CVEs total

CVE-2025-71400 7.1 HIGH better-auth passkey before 1.4.0 IDOR via delete-passkey
CVE-2025-71401 5.9 MEDIUM better-auth before 1.4.2 basePath Modification DoS

IV. Related Vulnerabilities

Same product: better-auth
Same vendor: better-auth
Same weakness: CWE-20

V. Comments for CVE-2025-71399

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