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CVE-2026-53518
Vulnerability in @better-auth/oauth-provider (CVE-2026-53518)
Summary
vulnerability in @better-auth/oauth-provider (CVE-2026-53518). Risk of unauthorized operations or information disclosure. Exploitable via `POST /oauth2/token`. Mitigation: upgrade to `1.6.11` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-53518** has been found in @better-auth/oauth-provider.
Attackers can target a specific entry point like `POST /oauth2/token` over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: ?/10.
What to do: upgrade @better-auth/oauth-provider to **1.6.11** or later.
If unsure, ask your IT team or search "@better-auth/oauth-provider CVE-2026-53518" on the vendor's site.
CVE-2026-53518 (@better-auth/oauth-provider) — CWE-294 /
Attack surface: POST /oauth2/token / `mcp` / `code` / `authorization_code`
Patched: `1.6.11` — 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-294) exists in @better-auth/oauth-provider. Attackers reach the vulnerable code path via `POST /oauth2/token` without authentication.
📍 Affected scope
@better-auth/oauth-provider — . Attack surface: POST /oauth2/token / `mcp` / `code` / `authorization_code`.
🔥 Severity
Severity: ?. Risk of unauthorized operations or information disclosure
🔧 How to fix
Update to **1.6.11**.
🛡️ 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 `POST /oauth2/token` requests with malformed payloads or SQL meta-characters. Run `grep -r '@better-auth/oauth-provider' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r '@better-auth/oauth-provider' . | 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/oauth-provider` を grep し、稼働しているサービス・バージョンを把握する。
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3Hunt for indicators of compromise detect
grep 'POST /oauth2/token' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで `POST /oauth2/token` への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。
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6Apply patch patch
Upgrade @better-auth/oauth-provider to 1.6.11ステージング環境で 1.6.11 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と、Step 3 で見つけた異常検知の続報チェックを含めること。
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7Post-deployment verification verify
Replay attack against POST /oauth2/token on staging to confirm patch closes the vector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 Step 3 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
npm
@better-auth/oauth-provider
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.11"}]}]
npm
better-auth
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.11"}]}]