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CVE-2025-71399 high CVSS 8.6

Vulnerability in better-auth (CVE-2025-71399)

Summary

Vulnerability in better-auth (CVE-2025-71399). Risk of unauthorized operations or information disclosure. Exploitable via disabledPaths. Mitigation: upgrade to 1.4.5 or later.

Original description

The description as published by the source.

Summary

An issue in the underlying router library rou3 can cause /path and //path to be treated as identical routes. If your environment does not normalize incoming URLs (e.g., by collapsing multiple slashes), this can allow bypasses of disabledPaths and path-based rate limits.

Details

Better Auth uses better-call, which internally relies on rou3 for routing. Affected versions of rou3 normalize paths by removing empty segments. As a result:

  • /sign-in/email
  • //sign-in/email
  • ///sign-in/email

…all resolve to the same route.

Some production setups automatically collapse multiple slashes. This includes:

In these environments and other configurations where //path reach Better Auth as /path, the issue does not apply.

Fix

Updating rou3 to the latest version resolves the issue:

Better Auth recommends:

  1. Upgrading to Better Auth v1.4.5 or later, which includes the updated rou3.
  2. Ensuring the proxy normalizes URLs.
  3. If project maintainers cannot upgrade yet, they can protect their…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2025-71399 has been found in better-auth.
Attackers can target a specific entry point like disabledPaths over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 8.6/10.
What to do: upgrade better-auth to 1.4.5 or later.
If unsure, ask your IT team or search "better-auth CVE-2025-71399" on the vendor's site.

CVE-2025-71399 (better-auth) — CWE-20 / CVSS v3 8.6
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: disabledPaths
Patched: 1.4.5 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-20) exists in better-auth. Attackers reach the vulnerable code path via disabledPaths without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of better-auth. Attack surface: disabledPaths.

🔥 Severity

Severity: High (CVSS 8.6/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 1.4.5.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'better-auth' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'better-auth' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で better-auth を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade better-auth to 1.4.5

    ステージング環境で 1.4.5 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

npm better-auth
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.4.5"}]}]

References

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