TI-2025-43515 Aliases CVE-2025-71399 GHSA-9fq7-6g6p-g9rm

Better Auth before 1.4.5 Path Normalization Bypass via rou3

MEDIUM 45CWE-20Published 2026-08-02 · Updated 2026-10-08

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: —
Confidentiality · integrity · availability: Low · Low · High
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.0052 44th percentileScored 2026-11-07

Fix Fixed better-auth (better-auth): 1.4.5

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
better-auth	better-auth	before 1.4.5	1.4.5	Patch available	CNA

better-auth Vendorbetter-auth Affected before 1.4.5 Fixed in 1.4.5 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:better-auth:better_auth::::::::	—	—	better-auth

cpe:2.3:a:better-auth:better_auth:*:*:*:*:*:*:*:* Versions — — ·better-auth

Remediation

Fix · CNA better-auth (better-auth) Fixed in 1.4.5

Timeline

2026-10-02 Threatist record created from CVE-2025-71399
2026-10-03 Alias added: GHSA-9fq7-6g6p-g9rm

References

Patch 1

Patch Commit

Advisory 1

GitHub Security Advisory (GHSA-x732-6j76-qmhm)

TI-2025-38277 Better Auth: Unauthenticated API key creation through api-key plugin CVSS 4.0CRITICAL 9.3
TI-2026-47627 better-auth SCIM 1.5.0 before 1.7.0-beta.4 Authorization Bypass CVSS 4.0HIGH 8.7
TI-2025-20000 Beter Auth has an Open Redirect via Scheme-Less Callback Parameter CVSS 4.0MEDIUM 6.9
TI-2026-13066 better-auth better-icons scan_project_icons/sync_icon path traversal CVSS 4.0MEDIUM 4.8
TI-2026-79320 OAuth state accepted as Magic Link token in Better Auth CVSS 3.1CRITICAL 9.1
TI-2026-74552 Authentication bypass in Better Auth Magic Link verification CVSS 4.0CRITICAL 9.3

See all 39 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences