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CVE-2026-53609 critical CVSS 9.1

Vulnerability in apostrophe (CVE-2026-53609)

Summary

vulnerability in apostrophe (CVE-2026-53609). Confidential information can be exposed externally. Exploitable via ``__proto__``. Mitigation: upgrade to `4.31.0` or later.

AI summary snake-internal / snake-material-v2

A vulnerability tracked as **CVE-2026-53609** has been found in apostrophe. Attackers can target a specific entry point like ``__proto__`` over the network to misuse the product. Confidential information can be exposed externally. CVSS score: 9.1/10. What to do: upgrade apostrophe to **4.31.0** or later. If unsure, ask your IT team or search "apostrophe CVE-2026-53609" on the vendor's site.
CVE-2026-53609 (apostrophe) — CWE-1321 / CVSS v3 9.1 Attack vector: remote (network-reachable) / no user interaction Attack surface: `__proto__` / `Object.prototype` / `constructor` / `prototype` Patched: `4.31.0` — 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-1321) exists in apostrophe. Attackers reach the vulnerable code path via ``__proto__`` without authentication.
📍 Affected scope
apostrophe — . Attack surface: `__proto__` / `Object.prototype` / `constructor` / `prototype`.
🔥 Severity
Severity: Critical (CVSS 9.1/10). Confidential information can be exposed externally
🔧 How to fix
Update to **4.31.0**.
🛡️ 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 'apostrophe' .` 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

  1. 1
    Identify exposure identify
    grep -r 'apostrophe' . | 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 `apostrophe` を grep し、稼働しているサービス・バージョンを把握する。

  2. 6
    Apply patch patch
    Upgrade apostrophe to 4.31.0

    ステージング環境で 4.31.0 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。

  3. 7
    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 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 apostrophe
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.31.0"}]}]

References

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