High severity · published Aug 2, 2026
CVE-2025-71399
Better Auth before 1.4.5 Path Normalization Bypass via rou3
8.6
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 44% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BE
better-auth · better-auth
before 1.4.5 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-71399
CVE.org
https://www.cve.org/CVERecord?id=CVE-2025-71399
vendor-advisory
https://github.com/better-auth/better-auth/security/advisories/GHSA-x732-6j76-qmhm
patch
https://github.com/better-auth/better-auth/commit/f60b43fa648399534507c9ac7db36d705b8874c3
third-party-advisory
https://www.vulncheck.com/advisories/better-auth-before-path-normalization-bypass-via-rou3
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